Evolutionary Psychological Science

, Volume 4, Issue 2, pp 191–201 | Cite as

Are Women Sexually Fluid? The Nature of Female Same-Sex Attraction and Its Evolutionary Origins

Theoretical Article

Abstract

The notion that female sexuality is fluid, meaning that women can experience attractions for either men or women depending on the circumstances, has been widely accepted by the academic community. Accordingly, scholars have attempted to develop evolutionary models that could explain why selection forces have favored sexual fluidity in women. The present paper reviews longitudinal studies on sexual attraction which indicate that the great majority of women do not have a fluid sexuality, but have instead stable attractions over time. Moreover, the current paper reviews studies on arousal, in order to demonstrate that they indicate a weak correlation between sexual arousal and sexual attraction in women, and not that women are attracted to both sexes. The evolutionary implications of the findings on female sexuality are further explored.

Keywords

Sexual fluidity Same-sex attraction Homosexuality Sexual arousal 

Introduction

Same-sex attraction is evolutionary puzzling: People who are attracted to members of the same sex are expected to suffer costs in their reproductive success, since they divert their limited resources toward outlets that cannot lead to child-bearing. On this basis, we would expect that strong negative selection pressures would remove from the gene pool any dispositions for same-sex attraction. Yet, this did not happen, with a considerable proportion of the population experiencing varying degrees of same-sex attraction (Dickson et al. 2013; LeVay 2010; Ott et al. 2011). In turn, the relative high prevalence of these dispositions in the population gave rise to much theorizing on their evolutionary origins (Bailey et al. 2016).

This theorizing focused predominantly on male same-sex attraction (LeVay 2010); yet, same-sex attraction is more common in women than in men (Calzo et al. 2017; Savin-Williams et al. 2012). Discovering the reasons for the high prevalence of same-sex attraction in women constitutes a major challenge for evolutionary scholars. For any such attempts to be fruitful, we first need to make clear what these attempts have to explain. Romantic and sexual attractions to opposite or same-sex individuals were seen as stable over time (LeVay 2010), a position which has been challenged (Baumeister 2000; Diamond 2008b). The purpose of the current paper is to review several lines of evidence in order to examine the nature of female same-sex attraction.

Sexual Fluidity

Sexual orientation is usually seen as an enduring pattern or disposition to experience sexual or romantic attractions toward people of the same sex, the other sex, or both sexes (Institute of Medicine 2011). This definition reflects the, until recently, prevailing position that sexual orientation is an early determined, stable trait that is highly resistant to change (Bell et al. 1981; Ellis and Ames 1987; Haldeman 1991; Money 1987). This position is supported by evidence from different lines of research, including conversion therapy outcome studies which, document very low success rates in treatment attempts to alter sexual orientation (Haldeman 1991, 1994), and studies suggesting a developmental continuity between gender-atypical behavior in childhood and later adult homosexuality (Bailey and Zucker 1995).

However, in her influential book “Sexual fluidity: Understanding women’s love and desire,” Diamond (2008b) suggested that women are sexually fluid: “Sexual fluidity simply means situation-dependent flexibility in women’s sexual responsiveness. This flexibility makes it possible for some women to experience attraction for either men or women under certain circumstances, regardless of their overall sexual orientation. In other words, although women -like men - appear to be born with distinct sexual orientations, these orientations are not the sole determining factor of their sexual attractions, and experiences. Instead, women of all orientations may experience variation in their erotic and affectional feelings as they encounter different situations, relationships, and life stages” (Diamond 2008b, p.3).

In this argument, women may undergo major changes in their sexual attractions, meaning that for instance, they may be attracted to women in one period and to men in a subsequent period. Diamond based her conclusions on a study that employed a sample of young non-heterosexual women and found that over a period of several years many of the participants in her sample changed their sexual identities from “lesbian,” to “bisexual,” to “heterosexual” and back again (Diamond 2008a). Accordingly, a label of “lesbian,” “bisexual,” or “heterosexual” may not be appropriate to describe these women and their sexuality may be better described.

The works of Diamond and other scholars (e.g., D’Augelli and Patterson 1995; Baumeister 2000) has led the academic community to the wide acceptance that the nature of female sexuality is fluid (Kuhle and Radtke 2013). The question arises, however, whether empirical studies on sexual orientation support the hypothesis of sexual fluidity. In a recent paper, Diamond (2016) reviewed several studies and concluded that there is support for the argument of sexual fluidity.

The first line of evidence she reviewed was studies on sexual orientation. These studies indicated that attractions to members of the same sex were more common in men than in women, and she interpreted this difference as evidence in favor of the sexual fluidity hypothesis. Yet, such difference could be the result of women being more fluid than men or from the fact that there are more women than men who have enduring attractions toward members of the same sex. Therefore, this sex difference is not evidence in favor of the sexual fluidity hypothesis. The second line of evidence she reviewed, referred to discrepancies between attraction and behavior. Across these studies, heterosexually identified women were more likely to report same-sex behavior than heterosexually identified men. Diamond argued that this sex difference constituted also evidence in support of the sexual fluidity argument, as sexual fluidity gives individuals a broad range of behavior options, depending on their circumstances. Still, as Diamond acknowledges, there are other explanations for this sex difference, such as the higher stigma ascribed to male than to female same-sex sexual contact, which in turn makes men less likely to engage or to report that they have engaged in it.

The most important evidence in support or lack of support for the sexual fluidity hypothesis comes from longitudinal studies on same-sex attraction. If the attractions of women are fluid, then women would experience changes in these attractions over time that would be detected by longitudinal studies. Diamond reviewed indeed some of these studies, but she focused on the data for non-heterosexual participants without taking into consideration data from heterosexual participants. The evidence she reviewed indicated that a considerable proportion of non-heterosexual women exhibited changes in their attractions over time. But, since the vast majority of individuals are heterosexuals, this is not evidence in favor of sexual fluidity in women, but evidence that non-heterosexual women may exhibit fluidity in their attractions.

We believe that there are sufficient longitudinal studies which can provide a solid answer to the question of whether women’s attractions are fluid. The next section will review these studies and examine whether the main predictions derived from the sexual fluidity hypothesis hold. Subsequently, it will examine the implication for evolutionary theorizing.

Longitudinal Studies on Sexual Attraction

In the sexual fluidity hypothesis, women have the capacity to be attracted to both sexes. Accordingly, in their lifetime, most women would have experienced attractions to both sexes, which in turn, lead to the prediction that when women are explicitly asked about their attractions, they would be unlikely to report that they are attracted exclusively to one sex. That is to say, the majority of women are not expected to see themselves as exclusively heterosexual. Furthermore, in this hypothesis, women are expected to experience considerable changes in their sexual attractions; they may for instance, in one period experience no or weak attraction to women, and in a different period strong attraction to women. In turn, this argument leads to the prediction that a substantial proportion of women would report changes in sexual attractions over time. Both predictions can be tested on evidence from studies which have examined how the attractions of women change over time.

Small Scale Studies

Weinberg et al. (1994) assessed changes in sexual attractions over a 5-year interval using a sample of 55 non-heterosexual individuals, comprising of people who were active participants in San Francisco’s newly emergent bisexual community in the early 1980s. They found that about two thirds of their respondents indicated changes in their self-reported ratio of same-sex to other-sex attractions over this 5-year period, whereas 85% indicated changes in their ratio of same-sex to other-sex sexual behavior. About half of these changes were toward the same sex and about 60% were 1-Kinsey point in magnitude (Kinsey scale ratings on a 0 to 6 scale, with 0 representing exclusive attraction to the opposite sex and 6 representing exclusive attraction to the same sex, see Kinsey et al. 1953).

Another study examined changes in self-identification among 156 gay, lesbian, and bisexual youths (Rosario et al. 2006). Over a 1-year period, 57% of the youths remained consistently self-identified as gay/lesbian, 18% transited from bisexual to gay/lesbian, and 15% consistently identified as bisexual. This study found also that, in contrary to the hypothesis that females are more sexually fluid than males, female youths were less likely to change identities than male youths.

Diamond studied a sample of 79 non-heterosexual women (i.e., women who identified as lesbian, bisexual, and unlabeled) over a period of 10 years (Diamond 2008a). Participants were assessed five times during this period, and it was found that 32% of women changed identities from T1 to T2, 25% from T2 to T3, 30% from T3 to T4, and 28% from T4 to T5. By the 10-year point, 67% of women had changed their identities at least once since T1, and 36% had changed identities more than once.

These studies were limited by the small samples of non-heterosexual participants. In particular, prevalence studies indicate that about 5% of women have a bisexual or homosexual orientation (Bailey et al. 2016; LeVay 2010; Yougov report 2015); therefore, by drawing small samples from this 5% it is not possible to draw conclusions for the 95% of women who differ specifically from the 5% in the dimension of interest. Thus, if more solid conclusions about female sexuality are to be reached, studies that include also heterosexual women are necessary.

Accordingly, one study collected 18-month follow-up data from 175 lesbian, bisexual, and heterosexual women (Pattatucci and Hamer 1995). The authors employed the Kinsey scale to measure same-sex attraction. Over the 18-month assessment period, they found that about 80% of the sample did not change their ratings, and those who did, changed their ratings typically by one point. This was, however, a small scale study, while the follow-up period was relatively short.

Overall, studies of non-heterosexual women found considerable change in women’s sexual attractions over time, but when heterosexual women were included in the sample, sexual attractions appeared to be much more stable. Still, all the studies above were based on small and non-representative samples, while only one study employed heterosexual women. Thus, in order to reach more solid conclusions about the nature of female sexuality, larger scale studies which will include representative samples of both heterosexual and non-heterosexual women, are necessary.

Large Scale Studies

Dickson et al. (2013), employed a cohort of 1037 participants born in Dunedin, New Zealand, between 1 April 1972 and 31 March 1973 (Dunedin Multidisciplinary Health and Development Study) in order to examine stability in attractions. Participants completed questions on sexual orientation at the age 21, 26, 32, and 38. As we can see from Table 1, across the different time periods, about 85% of women indicated exclusive attraction toward men. The most common form of same-sex attraction was to be predominantly attracted to men and occasionally to women with a prevalence rate of 11% across the different time periods.
Table 1

Estimates of different types of attraction across studies

Studies

Type of attraction

Calzo et al. 2017

Completely heterosexual (%)

Mostly heterosexual (%)

Bisexual (%)

Lesbian (%)

Unsure (%)

Missing (%)

Ages 12–13

85.8

3.7

0.4

0

5.4

4.7

Ages 14–15

89.6

5.4

1

0.1

1.1

2.8

Ages 16–17

87.7

8.4

1.7

0.2

0.6

1.6

Ages 18–19

86.7

9.9

1.8

0.6

0.2

0.8

Ages 20–21

84.2

12

2.4

0.9

0.4

0.1

Ages 22–23

80.7

15

2.4

1.4

0.3

0.2

Dickson et al. 2013

Only to opposite sex (%)

More often to opposite (%)

About equally to both (%)

More often to same (%)

Only to same (%)

No attraction (%)

Age 21

88.3

7.1

0.7

0.7

0.4

2.9

Age 26

82.5

14.5

0.9

0.4

0.9

0.9

Age 32

84.2

12.3

1.3

0.4

0.7

1.1

Age 38

87.6

9.4

1.5

0.2

0.9

0.4

Mock and Eibach 2012

Heterosexual (%)

Bisexual (%)

Homosexual (%)

   

Wave 1

98

1.2

0.8

   

Wave 2

97.4

1.5

1.2

   

Savin-Williams et al. 2012

100% heterosexual (%)

Mostly heterosexual (%)

Bisexual (%)

Mostly homosexual (%)

100% homosexual (%)

 

Wave 3

85.6

10.8

2.6

0.6

0.4

 

Wave 4

80.2

15.8

2.3

0.8

0.9

 
Stability of attraction was measured in three waves, namely, from 21 to 26 (wave 1), from 26 to 32 (wave 2), and from 32 to 38 years of age (wave 3). As we can see from Table 2, about 16% changed their responses in the first two waves, and about 12% changed their responses in wave 3. Those who indicated an attraction only to the opposite sex, indicated also a high stability, with about 11% changing the responses in wave 1 and less than 10% changing their responses in waves 2 and 3. The authors did not estimate stability for each form of same-sex attraction, but instead for broader forms of same-sex attraction. Thus, we can see that for forms of same-sex attraction between exclusive toward men and exclusive toward women, about 60% of participants changed their answers in each wave. For exclusive attraction to women, the change was 50% in the first two waves and 0% in the third wave. We cannot reach any solid conclusions for stability of exclusive same-sex attraction, as there were less than five women in this category.
Table 2

Estimates of stability of attraction across studies

Studies

Ott et al. 2011

Change in attraction (%)

    

Younger cohort

22.9

    

Older cohort

20.6

    

Dickson et al. 2013

Change in attraction (%)

Initially only opposite (%)

Initially mixed (%)

Initially only same (%)

 

Wave 1

16.1

11.5

60.5

50

 

Wave 2

16.3

7.6

58.9

50

 

Wave 3

11.8

4.2

58.1

0

 
 

Change in attraction

Heterosexual

Bisexual

Homosexual

 

Mock and Eibach 2012

     

Waves 1 to 2

2.6%

1.4%

64.7%

63.6%

 
 

Change in attraction

Heterosexual

Mostly heterosexual

Bisexual

Homosexual

Savin-Williams et al. 2012

     

Waves 3 to 4

17.8%

11.8%

47.2%

59.9%

26.6%

Another study examined reports of sexual orientation stability over a 10-year period drawing on data from the National Survey of Midlife Development in the USA (Mock and Eibach 2012) which included 2560 individuals. Sexual attraction was measured twice, once at the beginning of the study (wave 1) and 10 years later (wave 2) with responses of yes or no to the options “heterosexual (sexually attracted only to the opposite sex),” “homosexual (sexually attracted only to your own sex),” and “bisexual (sexually attracted to both men and women).” As we can see from Table 1, the vast majority of the 1370 female participants indicated that they were heterosexual. It needs to be said that this study was limited by not considering heterosexual orientation with same-sex attraction, which is in high prevalence rate in women. Thus, women who were exclusively heterosexuals, as well as those who were heterosexuals and experienced also same-sex attractions, had to respond that they were heterosexuals.

With respect to stability between the two waves, less than 3% of women changed their responses (Table 1). Heterosexual orientation was the most stable, since less than 2% of female participants who indicated to be heterosexuals in wave 1 changed their answers in wave 2. However, more than 60% of those who indicated that they were homosexuals or bisexuals in wave 1 changed their responses in wave 2.

Moving on, the Growing Up Today Study (GUTS) is a longitudinal cohort study of male and female adolescents living throughout the USA (Field et al. 1999). Self-identified sexual orientation was assessed biannually, and participants were asked to select one from several response options that best described their feelings. As we can see from Table 1, from a total of 7964 women, more than 80% identified as exclusively heterosexual (Calzo et al. 2017). The most common type of same-sex attraction was heterosexual with same-sex attractions which ranged from about 4% in the younger cohort to 15% in the older cohort.

For this sample, across four waves, Ott et al. (2011) estimated that for the women who were at the age of 12–17 when sexual attraction was first measured, about 23% changed their reported attraction, and for those who were at the age of 18–21, about 21% changed their reported attraction (Table 2). It was also estimated that across the four waves, at some point 10% of males and 20% of females described themselves as mostly heterosexual, bisexual, mostly homosexual, or completely homosexual, while 2%of both males and females reported ever being “unsure” of their orientation.

Savin-Williams et al. (2012) analyzed data for 12,287 men and women from a longitudinal study of a nationally representative sample of American individuals (National Longitudinal Study of Adolescent Health). In wave 3, where participants were between the ages of 18 and 24, about 85% of the 6556 women indicated that they were 100% heterosexuals, while in wave 4, where the participants’ age ranged from 24 to 34, about 80% of women identified that they were 100% heterosexuals. The most common form of same-sex attraction was heterosexual with same-sex attractions, with about 11% of women in wave 3 and 16% in wave 4 belonging to this category.

With respect to stability of attraction, in Table 2 we can see that, from wave 3 to wave 4, about 18% of women changed their responses. Exclusive heterosexual attraction was mostly stable: About 12% who indicated that they were exclusive heterosexuals in wave 3 changed their answers in wave 4. When we moved away from exclusive heterosexual orientation, the stability of responses fell considerably, with about one in two women who indicated that they were heterosexual with same-sex attraction and about 60% of women who indicated that they were bisexuals to change their answers between waves. This percentage fell to about 27% for homosexual women; yet, some caution is necessary in interpreting this result as only 64 women belonged to this category.

Furthermore, in wave 3, participants were asked to answer the question “Have you ever had a romantic attraction to women?”, whereas in wave 4, this question changed to “Are you romantically attracted to women?” Across the two waves, 87.5% of women answered “no” and 12.5% answered “yes” (Kanazawa 2017).

Retrospective Evidence

The conclusions of the longitudinal studies are supported also by evidence from a retrospective study which asked participants to recall the stability of their attractions. More specifically, Kinnish et al. (2005) recruited a sample of 762 individuals who had different sexual orientations and they were 35 years old or more. Participants were asked to provide information in three dimensions of sexual orientation (sexual fantasy, romantic attraction, sexual behavior) for 5-year periods beginning with age 16–20 (i.e., age 16–20, 21–25). Participants’ responses were measured using a 7-point Kinsey scale. Participants were also asked to indicate their sexual orientation in each period using a categorical scale (i.e., heterosexual, bisexual, gay/lesbian, or other).

With respect to the Kinsey scale responses, 51% of currently self-identified heterosexual, 1.5% of bisexual, and 9% of lesbian women reported no change ever for any dimension of orientation. In addition, 86% of heterosexual, 9% of bisexual, and 20% of lesbian women reported no more than a cumulative one point shift in any dimension over their entire adult lives.

Finally, with respect to the categorical sexual orientation scale, 3% of currently self-identified heterosexual, 77% bisexual women, and 64% of lesbian women reported one or more transitions in categorical sexual identity.

This retrospective study suffers from memory biases, meaning that part of the reported fluidity or stability may reflect inaccurate memories rather than actual shifts or stability of attractions. Even in the presence of such biases, the results are consistent with the results of the longitudinal studies: Heterosexual women, during their lifetime recalled high stability in their attractions, but non-heterosexual women recalled considerable less stability.

Further Considerations

On the basis of the finding of large scale longitudinal studies, we can attempt to estimate how many women are expected to exhibit some degree of sexual fluidity. To begin with, we averaged the percentages of women who indicated that they were attracted exclusively to men in the studies presented in Table 1. In our analysis, we did not include the Mock and Eibach (2012) study, because it did not distinguish between exclusive and not completely exclusive attraction to the opposite sex. Our estimate was 84.7%; accordingly, we can say that 84.7 out of 100 women are expected to be attracted exclusively to men. In order to find out how stable their attractions are expected to be, we averaged the percentages of change reported in Table 2 and we found 17.6%, which can be interpreted that out of 84.7 heterosexual women, 14.9 (84.7 × 0.176) are expected to experience change in their attractions.

In the same vein, 15.3% (100–84.7) are expected to experience some degree of same sex attraction. In order to find out how stable their attractions are expected to be, we averaged the percentages of change reported in Table 2 for all forms of same-sex attraction. We did not include the attraction to same-sex ratings from the Dickson et al. (2013) study, because of the very few observations in this category. Our estimation was 51.8%, which means that out of 15.3 women who are not exclusively heterosexual, 7.9 (15.3 × 0.518) are expected to experience changes in their attractions. Please note that, for simplicity, we did not weight our estimations for each type of same-sex attraction. In particular, mostly opposite-sex attraction with same-sex attraction is more common than exclusive same-sex attraction. Yet, because the stability rates for each category appear to be very similar (see Table 2), this simplification is reasonable.

Putting everything together, we would expect that out of 100 women, 22.8 (14.9 + 7.9) would experience some degree of change in their attractions. Although, exclusive attraction to the opposite sex is much more stable than the different types of same-sex attraction, most women who will exhibit fluidity, will come from the exclusive attraction to the opposite-sex category, because this is by far the largest one. We need to say that, some of the studies on which we based our estimations were not representative of the population, and not all age groups were represented, while each study had its own biases and limitations. It is unlikely however, that our estimations are far from the true ones. Thus, we can say that, about 77% of sexually mature women would experience stability and about 23% would experience fluidity in their attractions. These estimations indicate that the female sexuality cannot be characterized as fluid since the great majority of women do not experience changes in their attractions.

In addition, there are reasons to believe that the 23% who experiences sexual fluidity constitutes an overestimate. More specifically, Dickson et al. (2003), for the Dunedin Multidisciplinary Health and Development Study sample, compared women’s responses when they were 21 years old to their responses when they were 26 years old. They found that 84.4% of women did not indicate any change in their sexuality. From the remaining 15.6% who did, most (65.6%) changed their response from “being attracted only to the opposite sex” to “be attracted to the opposite sex but occasionally to the same sex.” The next biggest change (21.9%) was from “being attracted to the opposite sex but occasionally to the same sex” to “only to the opposite sex.” Similarly, Savin-Williams et al. (2012) estimated that responses between wave 3 and wave 4 and found that 17.8% percent of women did experience change in their attractions. The majority of those who changed their response (52%) moved from being attracted only to individuals of the opposite sex to being attracted mainly to individuals of the opposite sex. The second biggest change was from being attracted mainly to individuals of the opposite sex to being attracted only to individuals of the opposite sex (23.8%).

Thus, it seems that the majority of those who changed their responses, moved from being attracted exclusively to the opposite sex to being attracted predominantly to the opposite sex but occasionally to the same sex. This change, however, may not reflect an actual change in sexual attraction but the effect of maturity and experience. More specifically, younger individuals are less experienced and thus, less likely to be fully aware of their sexuality. In this scenario, sexual attraction may not have changed, but people have become more aware of it. It may also be the case that younger individuals are shyer and more reluctant than older ones to report their same-sex attractions, even if they are aware that they have them.

Furthermore, in both studies, the second biggest change was from being attracted predominantly to the opposite sex to be attracted exclusively to the opposite sex. This finding may also not reflect a genuine change in sexual attraction, but a better understanding of one’s sexuality that develops with age. For instance, individuals may have had some same-sex experiences out of curiosity or experimentation or after being prompted by a non-heterosexual individual. These experiences may have enabled participants to say that their attractions were mostly heterosexual when they were initially assessed, but as they aged, they may have come to realize that such response did not reflect their actual sexual attractions, so they altered their answers to exclusively heterosexual. As in the previous case, in this scenario sexual attraction did not undergo any change, but people became more aware of it. Consistent with the argument about maturity and experience effects, from Table 1 we can see that Calzo et al. (2017) estimated how the response for “unsure” about sexuality changed with age. We can observe a sharp decline from more than 5% in the 12–13 to 0.3% in the 22–23 age group.

It needs to be considered also that people’s responses may be affected by factors such as religious believes and religiosity. For instance, individuals may have experienced a traumatic event, such as the death of a relative that has turned them more religious. In many religious dogmas, such as Christianity, same sex attraction is not approved (Boswell 1980), so people who become more religious may actively attempt to suppress their attractions and be less willing to report them. Thus, longitudinal studies may detect a change in attraction, from some type of same-sex attraction to exclusive opposite-sex attraction, which however, is not real. In this sense, change in religiosity may inflate sexual fluidity rates. On the other hand, people who are very religious may refuse to acknowledge any changes in their attractions, and always declare that they are exclusively attracted to the opposite sex. In this respect, religiosity may deflate the true rate of fluidity.

The current literature does not allow us to distinguish between a genuine change in attraction and maturity, experience, and other effects. Although there are reasons to believe that the fluidity rates found in longitudinal studies are probably overestimates, it is reasonable to say that a considerable proportion of non-heterosexual women experience genuine shifts in their attractions.

Limitations and Directions for Future Research

The existing literature provides valuable evidence for the nature of female sexuality. We need to take into consideration nevertheless, that it has some limitations. In particular, there are few large scale longitudinal studies on sexual attraction which are confined to Western cultures. Accordingly, research on female sexuality would benefit from additional studies in different cultural settings. We consider it unlikely that such research would produce considerably different results, but some variation is expected. One reason is that attitudes toward same-sex attraction vary across cultural contexts (Fone 2000; LeVay 2010), which is likely to affect participants’ willingness to report their same-sex attractions.

The longitudinal studies reviewed in this paper, measured sexual attractions in time intervals which ranged from several months to several years. Other research methods could also be employed in order to investigate stability in attractions. For instance, a recent study has attempted to examine the day-to-day stability of women’s and men’s same-sex and other-sex attractions over a 30-day period using a non-probability sample of 294 heterosexual, lesbian, gay, and bisexual men and women (Diamond et al. 2017). Participants used online daily diaries to report the intensity of each day’s strongest same-sex and other-sex attraction.

It was found that women’s attractions showed less day-to-day stability than men’s, and interpreted this as evidence to be consistent with the notion of female sexual fluidity. Yet, there may be different explanations for this finding. Women, may for instance, experience higher variation in their day-to-day libido than men which reflects on their response patterns. Women are also less emotionally stable than men (Costa et al. 2001; Lynn and Martin 1997), which may affect their responses related to sexual attraction. Therefore, the sex difference in stability of attraction may not reflect differences in sexual fluidity but differences in libido or personality traits between the sexes. Future work needs to replicate this study, by keeping these factors constant.

Moreover, when assessing the evidence from the current literature, one may ask how big a change in participants’ responses should be in order to indicate a substantial change to sexual attraction. For instance, a one point change in the seven-point Kinsey scale may be interpreted by some scholars as indicating random noise between measurements rather than a genuine change in attraction. Other scholars could interpret this change to be a true shift in sexual attraction—people may have genuinely become more or less attracted to the same-sex. This is an issue that predominantly affects studies which have employed interval or Likert scales, and it is less of a problem for studies that have employed nominal scales in order to measure sexual attraction (e.g., heterosexual, homosexual). The reason is that, in the latter case, individuals classify themselves to different categories, and the distinctions are more clear-cut to reflect a random error. For instance, an individual who answered in one case “2” and in the other “3″” may not have experienced any true change in her attractions, but a woman who answered “Exclusive heterosexual” and subsequently “Heterosexual with same-sex attractions” has most likely experienced some change in her attractions.

Last but not least, as discussed above, most studies did not consider factors such as religiosity or a better understanding of one’s sexuality that comes with age, so their estimates of fluidity and stability suffer from biases. Future studies need to attempt to identify and control such confounding variables, in order to estimate more accurately the prevalence of sexual fluidity.

In summary, longitudinal studies on sexual attraction do not support the predictions derived from the sexual fluidity hypothesis: Most women do not experience attractions to both sexes, while most women’s attractions are stable over time. We will discuss next whether the argument for sexual fluidity is supported by evidence from research on sexual arousal.

Sexual Arousal Versus Sexual Attraction

Research on sexual arousal has produced evidence that may be interpreted as supportive of the sexual fluidity hypothesis. More specifically, studies on sexual arousal have found that most men are genitally aroused to one sex that is consistent with their reported sexual attractions, but women’s reported sexual attractions are weakly reflected in their genital responses because they are sexually aroused to both sexes (Bossio et al. 2014; Bouchard et al. 2017; Chivers et al. 2014; Chivers et al. 2004; Chivers et al. 2007; Huberman and Chivers 2015; Rieger et al. 2005). These findings were replicated with measures other than genital arousal, including pupil dilation while viewing sexual stimuli (Rieger et al. 2015; Rieger and Savin-Williams 2012), reaction time (Wright and Adams 1994; Wright and Adams 1999), and viewing time (Ebsworth and Lalumière 2012; Lippa 2012; Lippa 2013).

To discuss one recent study, Rieger et al. (2015) recruited a sample of 76 men and 72 women, and asked them to indicate their sexual attractions and fantasies toward men and women on a Kinsey-type scale. Subsequently, participants were asked to watch short videos depicting a naked person in a bedroom masturbating. The researchers recorded participants’ genital responses and pupil dilation in response to this stimulus. They found that both physiological measures indicated that, on average, women of all sexual orientations were physiologically aroused by both male and female stimuli.

In the sexual fluidity hypothesis, women’s sexual attractions are situation dependent, so that woman may experience attractions to both men and women. This being the case, women are expected to be aroused by both sexes, which is what is found in the existing studies. Yet, the arrow of causality does not go the other way round as well. That is, if women are aroused by both men and women, it does not mean that they are attracted to both men and women. As a matter of fact, the studies above demonstrated that women’s arousal patterns did not predict their sexual attractions. Most women who experienced arousal in the presence of both male and female sexual stimuli explicitly indicated that they were attracted only to men. It needs to be said also that women who were attracted predominantly to women, typically showed more sexual response to female than male sexual cues.

The finding that women are aroused by both male and female sexual stimuli is frequently misinterpreted to mean that most women are attracted also to other women, although it only means that the sexual arousal and sexual attraction in women are weakly correlated. For instance, the British newspaper “The Independent,” reported the results of a study on arousal (i.e., Rieger et al. 2016) in an article entitled “Women are never straight - they are either gay or bisexual, study suggests” (Osborne S. 2015). However, this research investigated the relationship between masculine and feminine behaviors and sexual arousal, and its findings do not support in any way the conclusion that women are never straight.

One argument that can be put forward is that studies on sexual attraction rely on self-report measures, and considering that same-sex attraction is a sensitive matter with discrimination and stigma associated to it (Fone 2000), participants may intentionally or unintentionally provide biased answers. On the other hand, studies on sexual arousal employ measures which are usually outside individuals’ conscious control, and may be therefore, more objective in measuring sexual attraction. For instance, pupils that dilate to stimuli indicate activation of the autonomic nervous system (Bradley et al. 2008; Lang and Bradley 2010), which is associated with many automatic processes such as perspiration, digestion, blood pressure, and heart rate (ten Donkelaar et al. 2011).

In this line of argumentation, the reason for the weak association between attraction and arousal is that women experience attraction and arousal to both sexes, but they underreport the former and cannot be dishonest about the latter. If this is correct, we would expect the same pattern to be observed in men; actually, because male same-sex attraction is stigmatized more than female same-sex attraction (Fone 2000), we would expect this pattern to be more pronounced in men than in women. But this is not what has been found. Men’s sexual arousal was strongly correlated with their attractions, i.e., men were aroused by what they indicate as desirable (Chivers et al. 2014; Huberman and Chivers 2015). Accordingly, the argument that sexual arousal studies provide a better measure for sexual attraction is unlikely to hold (see also Chivers 2017).

Exploring the evolutionary origins of this finding can shed further light to the phenomenon of weak correlation between attraction and arousal. In particular, it has been argued that women may have evolved to be sexually responsive in sexual context-dependent situations in order to avoid genital injury (Rieger et al. 2016). More specifically, there are reasons to believe that forced copulation has been present during most of the period of human evolution (Thornhill and Thornhill 1983 see also Apostolou 2013). Forced copulation can lead to genital trauma (Slaughter et al. 1997); therefore, the female response to any sexual stimuli could have evolved in part to mitigate this risk. Accordingly, women may have physiological sexual responses to a variety of sexual stimuli, including stimuli representing both consensual and forced sexual acts, sexual activities of nonhuman primates, and male and female sexual stimuli (Rieger et al. 2016).

Not all available data support an ultimate explanation of female sexual arousal (Dawson et al. 2015), but irrespectively of the ultimate reason, what the data support is that the women’s attractions and sexual arousal are weakly connected. Therefore, a stimulus that causes arousal to women does not necessary cause them sexual attraction. Accordingly, this line of research provides a wealth of evidence that enable us to understand female sexuality, but this evidence does not support or contradict the sexual fluidity hypothesis.

What Evolutionary Scholars Need to Explain?

Having adopted the hypothesis of sexual fluidity, evolutionary scholars have attempted to explain why selection forces have favored such fluidity in women. More specifically, Kuhle and Radtke (2013) argued that such fluidity potentially enabled women to secure help from other women in raising their children. Kanazawa (2017) argued that sexual fluidity benefited women who married polygynously as it reduced conflict with other women (but see Apostolou 2017). Yet, these hypotheses need to be revised in the light of evidence discussed in the sections above which indicates that the vast majority of women experience stable and not fluid attractions.

The evidence reviewed in this work indicates that the majority of women are exclusively attracted to men, with their attraction being stable over time. This evidence is consistent with evolutionary framework which proposes that mechanisms, including the ones regulating attraction, have evolved to enable individuals to gain access to the reproductive capacity of the opposite sex, and as such it does not require additional explaining. However, the literature reviewed indicates also that a significant proportion of women are not exclusively attracted to men, while their same-sex attractions are not always stable over time. This evidence seems inconsistent with the evolutionary reasoning as it appears to decrease women’s capacity to gain access to the opposite sex. Accordingly, evolutionary scholars have the challenge to explain why a considerable proportion of women exhibit attractions toward other women, and why such attractions are not always stable over time.

As sexual fluidity could potentially give flexibility to sexual response, the question arises why selection forces did not favor this trait in women. One reason is that fluidity could be potentially very costly in terms of fitness. More specifically, sexually fluid women may spend considerable time periods being attracted to members of the same-sex, which would place them in a disadvantageous position in relation to women who are consistently attracted exclusively or predominantly to men, and thus, would divert their mating effort toward outlets from which children can be born.

The longitudinal studies reviewed in this paper suggest that women who are not exclusively heterosexual exhibit considerable shifts in their attractions. The relative fluidity of same-sex attraction in women constitutes also a clue of its origins, and needs to be integrated in future theorizing. One possibility is that selection forces have favored fluid instead of stable same-sex attraction in women. In this respect, fluid same-sex attraction provided a stronger advantage in ancestral women than stable same-sex attraction.

Another possibility is that the relative instability that same-sex attraction exhibits is evidence that it has not been selected, but it is an outcome of weak negative selection pressures in ancestral human societies (Apostolou 2016). In such case, both mutant alleles that predispose for stable and unstable or fluid sexual orientation would remain in the gene pool. To put it differently, in the weak selection pressures scenario, the stability of same-sex attraction is of little consequence, since it does not serve a function so one type (stable/fluid) is not selected over another. In effect, both variations are expected to be present in the population.

Nevertheless, it can be argued that mutant alleles that predisposed for fluid same-sex attraction may have experienced weaker negative selection than mutant alleles that predisposed for stable same-sex attraction. If we assume that any form of female same-sex attraction has negative fitness effects, and through mutation, two alleles arise that predispose for same-sex attraction in women. The allele A predisposes for fluid same-sex attraction, while the allele B for stable same-sex attraction. A woman who carries the A, as opposed to a woman who carries the B, would be likely to spend periods of time during which she is not attracted at all to other women but only to men. In this respect, the negative selection pressures exercised on the A would be weaker than the ones exercised on the B, which in turn would lead to a higher frequency of the A in the gene pool, and thus, a higher fluidity of same-sex attraction.

One problem with the weak selection pressures hypothesis is that weak negative selection pressures may not be adequate to explain the high prevalence of same-sex attraction in women, and positive selection needs to be invoked (Gavrilets and Rice 2006). Accordingly, it has been argued that, one reason that has driven same-sex attraction in women in relatively high prevalence is male choice (Apostolou et al. 2017). Men who have as partners women who are attracted also to women, may face lower risk of cuckoldry as their partners can divert their sexual urges toward other women instead toward other men. Also, men can benefit by the same-sex attractions of their opposite-sex partners, as they can provide them with access to additional women. Evidence from two independent studies indicated that a considerable proportion of heterosexual men found same-sex attraction desirable in women (Apostolou et al. 2017). Analysis of men’s preferences indicated further that these men preferred heterosexual with same-sex attractions and not bisexual or homosexual women as partners. Thus, male choice would favor stable same-sex attraction manifested in heterosexual women rather than fluidity that would result in women experiencing attractions which are not desirable to men.

The observed prevalence rates of same-sex attraction in women are likely to have been the outcome of a combination of weak negative and positive selection pressures. Predispositions for stable and fluid same-sex attractions may have experienced weak negative selection pressures in ancestral human societies, predominantly due the regulation of mating. Such pressures would allow for a relative high prevalence rate of same-sex attraction, especially for fluid same-sex attraction. If a large proportion of men preferred same-sex attraction in heterosexual women, then alleles that predisposed for stable same-sex attraction in heterosexual women may have experienced positive selection and would be then in a relatively high frequency in the population. The combination of these two factors is likely to have resulted in a relative high frequency of same-sex attraction in the population, with many women experiencing stable and many women experiencing fluid attraction to the same sex.

In order to develop these arguments further, we need to examine what triggers change in same-sex attractions. More specifically, individual can experience changes in their attractions in a stochastic manner, or as a response to specific environmental triggers. If such changes are random, fluidity has probably no specific function and is the outcome of weak selection pressures. If, on the other hand, changes in attraction are the outcome of specific environmental triggers, this effect could be interpreted as evidence of positive selection on sexual fluidity. Identifying the causes of change is a major challenge for future research.

At this stage, the arguments above should be considered as theoretical possibilities, and much more theoretical and empirical work is necessary in order to understand the evolutionary origins of same-sex attraction in women.

Conclusions

Having a good understanding of female attractions and their stability is a necessary step toward understanding their evolutionary origins. Despite its limitations, the existing literature does not support the claim that women have a fluid sexuality. Instead, it indicates that the majority of women have stable sexual and romantic attractions. Yet, a considerable proportion of women experience attractions to other women, and a considerable proportion of these women experience also fluidity, meaning that their attractions change over time. At present, it remains unclear why selection forces have allowed or favored same-sex attraction in women, and why some women have stable and others fluid same-sex attractions. Evolutionary scholars need to employ the findings of the current literature on attraction in order to form solid theories that would enable us to understand the evolutionary origins of the same-sex attraction in women.

Notes

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

References

  1. Apostolou, M. (2013). The evolution of rape: the fitness benefits and costs of a forced-sex mating strategy in an evolutionary context. Aggression and Violent Behavior, 18, 484–490.CrossRefGoogle Scholar
  2. Apostolou, M. (2016). The evolution of female same-sex attractions: the weak selection pressures hypothesis. Evolutionary Behavioral Sciences, 10, 270–283.CrossRefGoogle Scholar
  3. Apostolou, M. (2017). Why sexual plasticity in women is unlikely to be an adaptation to reduce conflict in polygynous marriages. Archives of Sexual Behavior, 46, 329–330.CrossRefPubMedGoogle Scholar
  4. Apostolou, M., Shialos, M., Khalil, M., & Paschali, M. (2017). The evolution of female same-sex attraction: the male choice hypothesis. Personality and Individual Differences, 116, 372–378.CrossRefGoogle Scholar
  5. Bailey, J. M., & Zucker, K. J. (1995). Childhood sex-typed behavior and sexual orientation: a conceptual analysis and quantitative review. Developmental Psychology, 31, 43–55.CrossRefGoogle Scholar
  6. Bailey, J. M., Vasey, P. L., Diamond, L. M., Breedlove, S. M., Vilain, E., & Epprecht, M. (2016). Sexual orientation, controversy, and science. Psychological Science in the Public Interest, 17, 45–101.CrossRefPubMedGoogle Scholar
  7. Baumeister, R. F. (2000). Gender differences in erotic plasticity: the female sex drive as socially flexible and responsive. Psychological Bulletin, 126, 347–374.CrossRefPubMedGoogle Scholar
  8. Bell, A. P., Weinberg, M. S., & Hammersmith, S. K. (1981). Sexual preference: its development in men and women. Bloomington: Indiana University Press.Google Scholar
  9. Bossio, J. A., Suschinsky, K. D., Puts, D. A., & Chivers, M. L. (2014). Does menstrual cycle phase influence the gender specificity of heterosexual women’s genital and subjective sexual arousal? Archives of Sexual Behavior, 43, 941–952.CrossRefPubMedGoogle Scholar
  10. Boswell, J. (1980). Christianity, social tolerance and homosexuality: gay people in Western Europe from the beginning of the Christian era to the fourteenth century. Chicago: The University of Chicago Press.Google Scholar
  11. Bouchard, K. N., Chivers, M. L., & Pukal, C. F. (2017). Effects of genital response measurement device and stimulus characteristics on sexual concordance in women. The Journal of Sex Research. Advance Online Publication.Google Scholar
  12. Bradley, M. M., Miccoli, L., Escrig, M. A., & Lang, P. J. (2008). The pupil as a measure of emotional arousal and autonomic activation. Psychophysiology, 45, 602–607.CrossRefPubMedPubMedCentralGoogle Scholar
  13. Calzo, J. P., Masyn, K. E., Austin, S. B., Jun, H. J., & Corliss, H. L. (2017). Developmental latent patterns of identification as mostly heterosexual vs. lesbian, gay or bisexual. Journal of Research on Adolescence, 27, 246–253.CrossRefPubMedGoogle Scholar
  14. Chivers, M. L. (2017). The specificity of women’s sexual response and its relationship with sexual orientations: a review and ten hypotheses. Archives of Sexual Behavior. Advance Online Publication.Google Scholar
  15. Chivers, M. L., Rieger, G., Latty, E. M., & Bailey, J. M. (2004). A sex difference in the specificity of sexual arousal. Psychological Science, 15, 736–744.CrossRefPubMedGoogle Scholar
  16. Chivers, M. L., Seto, M. C., & Blanchard, R. (2007). Gender and sexual orientation differences in sexual response to sexual activities versus gender of actors in sexual films. Journal of Personality and Social Psychology, 93, 1108–1121.CrossRefPubMedGoogle Scholar
  17. Chivers, M. L., Roy, C., Grimbos, T., Cantor, J. M., & Seto, M. C. (2014). Specificity of sexual arousal for sexual activities in men and women with conventional and masochistic sexual interests. Archives of Sexual Behavior, 43, 931–940.CrossRefPubMedGoogle Scholar
  18. Costa Jr., P., Terracciano, A., & McCrae, R. R. (2001). Gender differences in personality traits across cultures: Robust and surprising findings. Journal of Personality and Social Psychology, 81, 322–331.CrossRefPubMedGoogle Scholar
  19. D’Augelli, A. R., & Patterson, C. J. (1995). Lesbian, gay, and bisexual identities over the lifespan: psychological perspectives. New York: Oxford University Press.CrossRefGoogle Scholar
  20. Dawson, S. J., Sawatsky, M. L., & Lalumière, M. L. (2015). Assessment of introital lubrication. Archives of Sexual Behavior, 44, 1527–1535.CrossRefPubMedGoogle Scholar
  21. Diamond, L. M. (2008a). Female bisexuality from adolescence to adulthood: results from a 10-year longitudinal study. Developmental Psychology, 44, 5–14.CrossRefPubMedGoogle Scholar
  22. Diamond, L. M. (2008b). Sexual fluidity: Understanding women’s love and desire. Cambridge, MA: Harvard University Press.Google Scholar
  23. Diamond, L. M. (2016). Sexual fluidity in male and females. Current Sexual Health Reports, 8, 249–256.CrossRefGoogle Scholar
  24. Diamond, L. M., Dickenson, J. A., & Blair, K. L. (2017). Stability of sexual attractions across different timescales: the roles of bisexuality and gender. Archives of Sexual Behavior, 46, 193–204.CrossRefPubMedGoogle Scholar
  25. Dickson, N., Paul, C., & Herbison, P. (2003). Same-sex attraction in a birth cohort: prevalence and persistence in early adulthood. Social Science and Medicine, 56, 1607–1615.CrossRefPubMedGoogle Scholar
  26. Dickson, N., van Roode, T., Cameron, C., & Paul, C. (2013). Stability and change in same-sex attraction, experience, and identity by sex and age in a New Zealand birth cohort. Archives of Sexual Behavior, 42, 753–763.CrossRefPubMedGoogle Scholar
  27. ten Donkelaar, H. J., Němcová, V., Lammens, M., Overeem, S., & Keyser, A. (2011). The Autonomic Nervous System. Clinical Neuroanatomy. Google Scholar
  28. Ebsworth, M., & Lalumière, M. L. (2012). Viewing time as a measure of bisexual sexual interest. Archives of Sexual Behavior, 41, 161–172.CrossRefPubMedGoogle Scholar
  29. Ellis, L., & Ames, M. A. (1987). Neurohormonal functioning and sexual orientation: a theory of homosexuality-heterosexuality. Psychological Bulletin, 101, 233–258.CrossRefPubMedGoogle Scholar
  30. Field, A. E., Camargo, C. A., Taylor, C. B., Berkey, C. S., Frazier, L., Gillman, M. W., et al. (1999). Overweight, weight concerns, and bulimic behaviors among girls and boys. Journal of the American Academy of Child and Adolescent Psychiatry, 38, 754–760.CrossRefPubMedGoogle Scholar
  31. Fone, B. (2000). Homophobia: A history. New York: Picador.Google Scholar
  32. Gavrilets, S., & Rice, W. R. (2006). Genetic models of homosexuality: Generating testable predictions. Proceeding of the Royal Society B, 273, 3031–3038.CrossRefGoogle Scholar
  33. Haldeman, D. C. (1991). Sexual conversion therapy for gay men and lesbians: a scientific examination. In J. C. Gonsiorek & J. D. Weinrich (Eds.), Homosexuality: Research implications for public policy (pp. 149–160). Newbury Park, CA: Sage.CrossRefGoogle Scholar
  34. Haldeman, D. C. (1994). The practice and ethics of sexual orientation conversion therapy. Journal of Consulting and Clinical Psychology, 62, 221–227.CrossRefPubMedGoogle Scholar
  35. Huberman, J. S., & Chivers, M. L. (2015). Examining gender specificity of sexual response with concurrent thermography and plethysmography. Psychophysiology, 52, 1382–1395.CrossRefPubMedGoogle Scholar
  36. Institute of Medicine. (2011). The health of lesbian, gay, bisexual, and transgender people: building a foundation for better understanding. Washington, D.C: The National Academies Press.Google Scholar
  37. Kanazawa, S. (2017). Possible evolutionary origins of human female sexual fluidity. Biological Reviews, 92, 1251–1274.CrossRefPubMedGoogle Scholar
  38. Kinnish, K. K., Strassberg, D. S., & Turner, C. W. (2005). Sex differences in the flexibility of sexual orientation: a multidimensional retrospective assessment. Archives of Sexual Behavior, 34, 173–183.CrossRefPubMedGoogle Scholar
  39. Kinsey, A., Pomeroy, W., Martin, C., & Gebhard, P. (1953). Sexual behavior in the human female. Philadelphia: Saunders.Google Scholar
  40. Kuhle, B. X., & Radtke, S. (2013). Born both ways: the alloparenting hypothesis for sexual fluidity in women. Evolutionary Psychology, 11, 304–323.CrossRefPubMedGoogle Scholar
  41. Lang, P. J., & Bradley, M. M. (2010). Emotion and the motivational brain. Biological Psychology, 84, 437–450.CrossRefPubMedGoogle Scholar
  42. LeVay, S. (2010). Gay, straight, and the reason why: the science of sexual orientation. Oxford: Oxford University Press.Google Scholar
  43. Lippa, R. A. (2012). Effects of sex and sexual orientation on self-reported attraction and viewing times to images of men and women: testing for category specificity. Archives of Sexual Behavior, 41, 149–160.CrossRefPubMedGoogle Scholar
  44. Lippa, R. A. (2013). Men and women with bisexual identities show bisexual patterns of sexual attraction to male and female “swimsuit models”. Archives of Sexual Behavior, 42, 187–196.CrossRefPubMedGoogle Scholar
  45. Lynn, R., & Martin, T. (1997). Gender differences in extraversion, neuroticism, and psychoticism in 37 nations. Journal of Social Psychology, 137, 369–373.CrossRefPubMedGoogle Scholar
  46. Mock, S. E., & Eibach, R. P. (2012). Stability and change in sexual orientation identity over a 10-year period in adulthood. Archives of Sexual Behavior, 41, 641–648.CrossRefPubMedGoogle Scholar
  47. Money, J. (1987). Sin, sickness, or status? Homosexual gender identity and psychoneuroendrocrinology. American Psychologist, 43, 384–399.CrossRefGoogle Scholar
  48. Ott, M. Q., Corliss, H. L., Wypij, D., Rosario, M., & Austin, S. B. (2011). Stability and change in self-reported sexual orientation identity in young people: application of mobility metrics. Archives of Sexual Behavior, 40, 519–532.CrossRefPubMedGoogle Scholar
  49. Osborne, S. Women are never straight—they are either gay or bisexual, study suggests. (2015, November, 5). Retrieved from: http://www.independent.co.uk/life-style/love-sex/women-are-never-straight-they-are-either-gay-or-bisexual-study-suggests-a6723276.html.
  50. Pattatucci, A. M. L., & Hamer, D. H. (1995). Development and familiality of sexual orientation in females. Behavior Genetics, 25, 407–420.CrossRefPubMedGoogle Scholar
  51. Rieger, G., & Savin-Williams, R. C. (2012). The eyes have it: sex and sexual orientation differences in pupil dilation patterns. PLoS One, 7, e40256.CrossRefPubMedPubMedCentralGoogle Scholar
  52. Rieger, G., Chivers, M. L., & Bailey, J. M. (2005). Sexual arousal patterns of bisexual men. Psychological Science, 16, 579–584.CrossRefPubMedGoogle Scholar
  53. Rieger, G., Cash, B. M., Merrill, S. M., Jones-Rounds, J., Dharmavaram, S. M., & Savin Williams, R. C. (2015). Sexual arousal: the correspondence of eyes and genitals. Biological Psychology, 104, 56–64.CrossRefPubMedGoogle Scholar
  54. Osborne, S. (2015) Women are never straight—they are either gay or bisexual, study suggests. Retrieved from: http://www.independent.co.uk/life-style/love-sex/women-are-never-straight-they-are-either-gay-or-bisexual-study-suggests-a6723276.html.
  55. Rieger, G., Savin-Williams, R. C., Chivers, M. L. & Bailey, M. J. (2016). Sexual arousal and masculinity-femininity of women. Journal of Personality and Social Psychology. Advance Online Publication.Google Scholar
  56. Rosario, M., Schrimshaw, E. W., Hunter, J., & Braun, L. (2006). Sexual identity development among lesbian, gay, and bisexual youths: consistency and change over time. Journal of Sex Research, 43, 46–58.CrossRefPubMedPubMedCentralGoogle Scholar
  57. Savin-Williams, R. C., Joyner, K., & Rieger, G. (2012). Prevalence and stability of self-reported sexual orientation identity during young adulthood. Archives of Sexual Behavior, 41, 103–110.CrossRefPubMedGoogle Scholar
  58. Slaughter, L., Brown, C. R. V., Crowley, S., & Peck, R. (1997). Patterns of genital injury in female sexual assault victims. American Journal of Obstetrics and Gynecology, 176, 609–616.CrossRefPubMedGoogle Scholar
  59. Thornhill, R., & Thornhill, N. W. (1983). Human rape: an evolutionary analysis. Ethology and Sociobiology, 4, 137–173.CrossRefGoogle Scholar
  60. Weinberg, M. S., Williams, C. J., & Pryor, D. W. (1994). Dual attraction: understanding bisexuality. New York: Oxford University Press.Google Scholar
  61. Wright Jr., L., & Adams, H. (1994). Assessment of sexual preference using a choice reaction time task. Journal of Psychopathology and Behavioral Assessment, 16, 221–231.CrossRefGoogle Scholar
  62. Wright Jr., L. W., & Adams, H. E. (1999). The effects of stimuli that vary in erotic content on cognitive processes. Journal of Sex Research, 36, 145–151.CrossRefGoogle Scholar

Copyright information

© Springer International Publishing AG, part of Springer Nature 2017

Authors and Affiliations

  1. 1.Department of Social SciencesUniversity of NicosiaNicosiaCyprus

Personalised recommendations