Human Genetics

, Volume 118, Issue 6, pp 691–694 | Cite as

Extreme skewing of X chromosome inactivation in mothers of homosexual men

  • Sven Bocklandt
  • Steve Horvath
  • Eric Vilain
  • Dean H. Hamer
Original Investigation

Abstract

Human sexual preference is a sexually dimorphic trait with a substantial genetic component. Linkage of male sexual orientation to markers on the X chromosome has been reported in some families. Here, we measured X chromosome inactivation ratios in 97 mothers of homosexual men and 103 age-matched control women without gay sons. The number of women with extreme skewing of X-inactivation was significantly higher in mothers of gay men (13/97=13%) compared to controls (4/103=4%) and increased in mothers with two or more gay sons (10/44=23%). Our findings support a role for the X chromosome in regulating sexual orientation in a subgroup of gay men.

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Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Sven Bocklandt
    • 1
    • 3
    • 4
  • Steve Horvath
    • 1
    • 2
  • Eric Vilain
    • 1
  • Dean H. Hamer
    • 3
  1. 1.Department of Human GeneticsUniversity of CaliforniaLos AngelesUSA
  2. 2.Department of BiostatisticsUniversity of CaliforniaLos AngelesUSA
  3. 3.Laboratory of BiochemistryNational Cancer InstituteBethesdaUSA
  4. 4.Los AngelesUSA

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