Theoretical Medicine and Bioethics

, Volume 39, Issue 1, pp 27–56 | Cite as

The ethics of separating conjoined twins: two arguments against

  • Luke KallbergEmail author


I argue that the separation of conjoined twins in infancy or early childhood is unethical (rare exceptions aside). Cases may be divided into three types: both twins suffer from lethal abnormalities, only one twin has a lethal abnormality, or neither twin does. In the first kind of case, there is no reason to separate, since both twins will die regardless of treatment. In the third kind of case, I argue that separation at an early age is unethical because the twins are likely to achieve an irreplaceably good quality of life—the goods of conjoinment—that separation takes away. Evaluation of this possibility requires maturation past early childhood. Regarding the second type, I point out that with conceivable but unrecorded exceptions, these cases will consistently involve sacrifice separation. I present an argument that sacrifice separation is unethical, but in some cases a moral dilemma may exist in which separation and refraining from separation are both unethical. Perhaps in such cases a decision can be made on non-moral grounds; however, the possibility of such a decision serves not to mitigate but to underscore the fact that the separation is unethical. My conclusion, which applies to all three types of cases, is that it is unethical to separate conjoined twins before their developing personalities give some reliable indication as to whether they desire separation and whether they will achieve those goods of conjoinment.


Conjoined twins Quality of life Autonomy Organ transplantation Self-defense Necessity (legal doctrine) Moral dilemmas 



I would like to thank Jeff Bishop for many fruitful conversations about this paper, as well as several anonymous reviewers for their critiques and Katelyn MacDougald for editorial suggestions that greatly improved the paper.


  1. 1.
    Whitfield, Adrian, Oliver O’Donavan, and Lewis Spitz. 2002. The conjoined twins: Transcript of the speeches given at the BAFS annual dinner on 28 February 2002. Medicine, Science and the Law 42: 277–287.CrossRefGoogle Scholar
  2. 2.
    Rode, H., A.G. Fieggan, R.A. Brown, S. Cywes, M.R.Q. Davies, J.P. Hewitson, E.B. Hoffman, et al. 2006. Four decades of conjoined twins at Red Cross Children’s Hospital—Lessons learned. South African Medical Journal 96: 931–940.Google Scholar
  3. 3.
    Millar, Alistar J.W., Heinz Rode, Jenny Thomas, and John Hewitson. 2009. Thoracopagus conjoined twins. In Pediatric thoracic surgery, ed. Dakshesh H. Parikh, David C.G. Crabbe, Alexander W. Auldist and Steven S. Rothernberg, 557–568. New York: Springer.CrossRefGoogle Scholar
  4. 4.
    Thomas, Jennifer. 2011. Anesthesia for conjoined twins. In Smith’s anesthesia for infants and children. 8th ed, ed. Peter J. Davis, Franklyn P. Cladis and Etsuro K. Motoyama, 950–970. Philadelphia: Elsevier.CrossRefGoogle Scholar
  5. 5.
    Spencer, Rowena. 2003. Conjoined twins: Developmental malformations and clinical implications. Baltimore: Johns Hopkins University Press.Google Scholar
  6. 6.
    Spitz, Lewis. 2015. Ethics in the management of conjoined twins. Seminars in Pediatric Surgery 24: 263–264.CrossRefGoogle Scholar
  7. 7.
    Spitz, Lewis. 2006. Conjoined twins. In Operative pediatric surgery. 6th ed, ed. Lewis Spitz and Arnold Coran, 1047–1051. Boca Raton: CRC Press.CrossRefGoogle Scholar
  8. 8.
    Russell, Daniel C. 2012. Happiness for humans. Oxford: Oxford University Press.CrossRefGoogle Scholar
  9. 9.
    Haybron, Daniel M. 2008. The pursuit of unhappiness: The elusive psychology of well-being. New York: Oxford University Press.Google Scholar
  10. 10.
    Bishop, Michael A. 2015. The good life: Unifying philosophy and psychology of well-being. Oxford: Oxford University Press.CrossRefGoogle Scholar
  11. 11.
    Dreger, Alice Domurat. 2004. One of us: Conjoined twins and the future of normal. Cambridge: Harvard University Press.Google Scholar
  12. 12.
    Greenwood, Carl. 2015. Family’s heartache as five-year-old conjoined twin dies after 18-hour operation to separate him from his brother. Mirror, September 9. Accessed February 7, 2017.
  13. 13.
    Quigley, Christine. 2006. Conjoined twins: An historical, biological, and ethical issues encyclopedia. Jefferson: McFarland.Google Scholar
  14. 14.
    Al Rabeeah, Abdullah. 2006. Conjoined twins—Past, present, and future. Journal of Pediatric Surgery 41: 1000–1004.CrossRefGoogle Scholar
  15. 15.
    Spitz, Lewis, and Edward M. Kiely. 2003. Conjoined twins. Journal of the American Medical Association 289: 1307–1310.CrossRefGoogle Scholar
  16. 16.
    Mainous, Rosalie O. 2002. Conjoined twins: Whose best interest should prevail? An argument for separation. Pediatric Nursing 28: 525–529.Google Scholar
  17. 17.
    Thomas, Jenny M., and J. Tessa Lopez. 2004. Conjoined twins—The anesthetic management of 15 sets from 1991–2002. Pediatric Anesthesia 14: 117–129.CrossRefGoogle Scholar
  18. 18.
    Spencer, Rowena. 1956. Surgical separation of Siamese twins: Case report. Surgery 39: 827–833.Google Scholar
  19. 19.
    Kiesewetter, William B. 1966. Surgery on conjoined (Siamese) twins. Surgery 59: 860–871.Google Scholar
  20. 20.
    Guttmacher, A.F. 1967. Biographical notes on some famous conjoined twins. Birth Defects Original Article Series 3: 10–17.Google Scholar
  21. 21.
    Pepper, C.K. 1967. Ethical and moral considerations in the separation of conjoined twins. Birth Defects Original Article Series 3: 128–134.Google Scholar
  22. 22.
    Golladay, E.S., G. Doyne Williams, Joanna J. Seibert, W.T. Dungan, and Ray Shenefelt. 1982. Dicephalus dipus conjoined twins: A surgical separation and review of previously reported cases. Journal of Pediatric Surgery 17: 259–264.CrossRefGoogle Scholar
  23. 23.
    Hilfiker, Mary L. 2003. Conjoined twins. In Operative pediatric surgery, ed. Moritz M. Ziegler, Rishard Z. Azizkhan and Thomas R. Weber, 1063–1072. New York: McGraw-Hill.Google Scholar
  24. 24.
    Schuknecht, H.F. 1979. The Siamese twins, Eng and Chang: Their lives and their hearing losses. Archives of Otolaryngology 105: 737–740.CrossRefGoogle Scholar
  25. 25.
    Stated meeting, February 19. 1841. Proceedings of the American Philosophical Society 2: 17–28.Google Scholar
  26. 26.
    Martell, Joanne. 2000. Millie-Christine: Fearfully and wonderfully made. Winston-Salem: Blair.Google Scholar
  27. 27.
    Samuels, Ellen. 2011. Examining Millie and Christine McKoy: Where enslavement and enfreakment meet. Signs: Journal of Women in Culture and Society 37: 53–81.CrossRefGoogle Scholar
  28. 28.
    The Tocci twins. 1891. Scientific American 65: 374.Google Scholar
  29. 29.
    Harris, Robert P. 1892. The blended Tocci brothers and their historical analogues. American Journal of Obstetrics and Diseases of Women and Children 25: 460–473.Google Scholar
  30. 30.
    Bondeson, Jan. 2000. The two-headed boy and other medical marvels. Ithaca: Cornell University Press.Google Scholar
  31. 31.
    Sullivan, Louis R. 1919. The “Samar” united twins. American Journal of Physical Anthropology 2: 21–24.CrossRefGoogle Scholar
  32. 32.
    Eagle, Robert (prod.), and James van der Pool (dir.). 2000. Conjoined twins. In Horizon, October 19. London: British Broadcasting Corporation.Google Scholar
  33. 33.
    Guinness world records. 2015. Guinness world records 2016. London: Guinness World Records.Google Scholar
  34. 34.
    Cady, Marlene. 1989. The pure joy of being alive. People, July 3, 64–71.Google Scholar
  35. 35.
    ‘Abby and Brittany’ finale: Conjoined twins get teaching job. 2012. Huffington Post, October 3. Accessed February 5, 2018.
  36. 36.
    Moye, David. 2014. Conjoined twins refuse to be separated. Huffington Post, April 10. Accessed February 5, 2018.
  37. 37.
    Woodfill, D.S. 2010. Conjoined twins from QC area die in surgery. Arizona Republic, August 13, B1.Google Scholar
  38. 38.
    Zeiger, Dan. 2011. Run honoring deceased conjoined twins to cease. East Valley Tribune, February 25.Google Scholar
  39. 39.
    Cameron, D.E., B.A. Reitz, B.S. Carson, D.M. Long, C.R. Dufresne, C.A. Vander Kolk, L.G. Maxwell, et al. 1989. Separation of craniopagus Siamese twins using cardiopulmonary bypass and hypothermic circulatory arrest. Journal of Thoracic and Cardiovascular Surgery 98: 961–967.Google Scholar
  40. 40.
    Associated Press. 1989. Binder twins far from normal two years after surgery. AP News Archive, June 26. Accessed December 12, 2015.
  41. 41.
    Bor, Jonathan. 1998. Parted twins’ future bright: Surgery: After a virtual reality rehearsal, a Johns Hopkins doctor leads the successful separation of Zambian joined-at-the-head twins. Baltimore Sun, January 11. Accessed January 19, 2016.
  42. 42.
    Miller, Kenneth. 1996. Together forever. Life, April, 44–56.Google Scholar
  43. 43.
    Wallis, Claudia. 1996. The most intimate bond. Time, March 25, 60–64.Google Scholar
  44. 44.
    Amelon, Kandi (prod.). 1996. The Oprah Winfrey show, April 8. Chicago: Harpo Productions.Google Scholar
  45. 45.
    Hayes, Bill (dir.). 2003. Joined for life. Silver Spring: Discovery Channel.Google Scholar
  46. 46.
    Pihlaja, Rachael (prod. and dir.). 2007. The twins who share a body. In Extraordinary people, February 19. Leeds: True North Productions.Google Scholar
  47. 47.
    Glover, Beth (prod. and dir.). 2012. Abby and Brittany. Silver Spring: TLC.Google Scholar
  48. 48.
    Wallis, Lucy. 2013. Living a conjoined life. BBC News Magazine, April 25.Google Scholar
  49. 49.
    Pihlaja, Rachael (prod. and dir.). 2006. Joined for life: Abby and Brittany turn 16. Silver Spring: TLC.Google Scholar
  50. 50.
    Perslstein, M.A., and E.R. LeCount. 1927. Pygopagus twins: The history and necropsy report of the Bohemian twins, Rosa-Josepha Blazek. Archives of Pathology and Laboratory Medicine 3: 171–192.Google Scholar
  51. 51.
    Taylor, James, and Kathleen Kotcher. 2002. “Shocked and amazed!” On and off the midway. Guilford: Lyons Press.Google Scholar
  52. 52.
    Brierley, Kerry (prod. and dir.), and Laura Chapnick (prod.). 2010. World’s oldest conjoined twins move home. Silver Spring: TLC.Google Scholar
  53. 53.
    Smith, J. David. 1988. Psychological profiles of conjoined twins: Heredity, environment, and identity. New York: Praeger.Google Scholar
  54. 54.
    Minuchin, Salvador. 1974. Families and family therapy. Cambridge: Harvard University Press.Google Scholar
  55. 55.
    Petrician, Raluca, Christopher T. Burris, Tania Bielack, Ulrich Schimmack, and Morris Moscovitch. 2011. For my eyes only: Gaze control, enmeshment, and relationship quality. Journal of Personality and Social Psychology 100: 1111–1123.CrossRefGoogle Scholar
  56. 56.
    Haidt, Jonathan. 2006. The happiness hypothesis: Finding modern truth in ancient wisdom. New York: Basic Books.Google Scholar
  57. 57.
    Nelson, Janice, and Frances E. Aboud. 1985. The resolution of social conflict between friends. Child Development 56: 1009–1017.CrossRefGoogle Scholar
  58. 58.
    Koh, Yun-Joo, Morton J. Mendelson, and Unhai Rhee. 2003. Friendship satisfaction in Korean and Canadian university students. Canadian Journal of Behavioral Science 35: 239–253.CrossRefGoogle Scholar
  59. 59.
    Fincham, Frank D., Steven R.H. Beach, and Joanne Davila. 2003. Forgiveness and conflict resolution in marriage. Journal of Family Psychology 18: 72–81.CrossRefGoogle Scholar
  60. 60.
    Fincham, Frank D., Steven R.H. Beach, and Joanne Davila. 2007. Longitudinal relations between forgiveness and conflict resolution in marriage. Journal of Family Psychology 21: 542–545.CrossRefGoogle Scholar
  61. 61.
    Swann Jr., William B., Chris De La Ronde, and J. Gregory Hixon. 1994. Authenticity and positivity strivings in marriage and courtship. Journal of Personality and Social Psychology 66: 857–869.CrossRefGoogle Scholar
  62. 62.
    Impett, Emily A., Leyla Javam, Bonnie M. Le, Behzad Asyabi-Eshghi, and Aleksandr Kogan. 2013. The joys of genuine giving: Approach and avoidance sacrifice motivation and authenticity. Personal Relationships 20: 740–754.CrossRefGoogle Scholar
  63. 63.
    Rotenberg, Ken J., and Michael Boulton. 2013. Interpersonal trust consistency and the quality of peer relationships during childhood. Social Development 22: 225–241.CrossRefGoogle Scholar
  64. 64.
    Harris, V.William, Linda Skogrand, and Daniel Hatch. 2008. Role of friendship, trust, and love in strong Latino marriages. Marriage and Family Review 44: 455–488.CrossRefGoogle Scholar
  65. 65.
    Canevello, Amy, and Jennifer Crocker. 2010. Creating good relationships: Responsiveness, relationship quality, and interpersonal goals. Journal of Personal Social Psychology 99: 78–106.CrossRefGoogle Scholar
  66. 66.
    Gevers, Anik, Rachel Jewkes, and Cathy Mathews. 2013. What do young people think makes their relationships good? Factors associated with assessments of dating relationships in South Africa. Culture, Health and Sexuality 15: 1011–1025.CrossRefGoogle Scholar
  67. 67.
    Murray, Craig D. 2001. The experience of body boundaries by Siamese twins. New Ideas in Psychology 19: 117–130.CrossRefGoogle Scholar
  68. 68.
    Bogdan, Robert. 1988. Freak show: Presenting human oddities for amusement and profit. Chicago: University of Chicago Press.Google Scholar
  69. 69.
    Baker, Mark. 2003. Together and apart. The Age, June 13. Accessed December 12, 2015.
  70. 70.
    Devettere, Raymond J. 2010. Practical decision making in health care ethics: Cases and concepts. Washington, DC: Georgetown University Press.Google Scholar
  71. 71.
    O’Brien, Margaret (prod.), and Judith Pyke (dir.). 2013. Twin life: Sharing mind and body. In Doc zone, March 13. Ottawa: Canadian Broadcasting Corporation.Google Scholar
  72. 72.
    Usher, Michael, and Phil Goyen (prod.). 2012. The amazing Hogan twins. In 60 minutes [Australia], May 27. Sydney: Nine Network.Google Scholar
  73. 73.
    Tatiana and Krista travel fund. 2014. GoFundMe. Accessed January 21, 2016.
  74. 74.
    Savulescu, Julian, and Ingmar Persson. 2016. Conjoined twins: Philosophical problems and ethical challenges. Journal of Medicine and Philosophy 41: 41–55.Google Scholar
  75. 75.
    Separated Vietnamese conjoined twin dies. 2007. The Japan Times, October 7. Accessed January 17, 2016.
  76. 76.
    Cleveland, Sidney E., E. Edward Reitman, and Diana Sheer. 1964. Psychological appraisal of conjoined twins. Journal of Projective Techniques and Personality Assessment 28: 265–270.Google Scholar
  77. 77.
    Jones, Stewart H., Omar Z. Younghusband, and James A. Evans. 1948. Human parabiotic pygopagus twins with hypertension. Journal of the American Medical Association 138: 642–645.Google Scholar
  78. 78.
    Thomasma, David C., Jonathan Muraskas, Patricia A. Marshall, Thomas Myers, Paul Tomich, and James A. O’Neill Jr. 1996. The ethics of caring for conjoined twins: The Lakeberg twins. Hastings Center Report 26: 4–12.CrossRefGoogle Scholar
  79. 79.
    A (Children), Re [2000] EWCA Civ 254 (22 September 2000); [2001] 2 WLR 480. Accessed November 19, 2015.
  80. 80.
    Annas, George. 2001. Conjoined twins—The limits of law at the limits of life. New England Journal of Medicine 344: 1104–1108.CrossRefGoogle Scholar
  81. 81.
    van Inwagen, Peter. 1990. Material beings. Ithaca: Cornell University Press.Google Scholar
  82. 82.
    McMahan, Jeff. 2002. The ethics of killing: Problems at the margins of life. New York: Oxford University Press.CrossRefGoogle Scholar
  83. 83.
    Foot, Philippa. 1967. The problem of abortion and the doctrine of double effect. Oxford Review 5: 28–41.Google Scholar
  84. 84.
    Thomson, Judith Jarvis. 1976. Killing, letting die, and the trolley problem. Monist 59: 204–217.CrossRefGoogle Scholar
  85. 85.
    Carritt, Edgar F. 1947. Ethical and political thinking. Oxford: Oxford University Press.Google Scholar
  86. 86.
    McCloskey, H.J. 1965. A non-utilitarian approach to punishment. Inquiry 8: 239–255.CrossRefGoogle Scholar
  87. 87.
    Sinnott-Armstrong, Walter. 2015. Consequentialism. Accessed January 22, 2016.
  88. 88.
    Lawson, Craig M. 2001. The puzzle of intended harm in the tort of battery. Temple Law Review 74: 355–386.Google Scholar
  89. 89.
    Jensen, Stephen J. 2011. The ethics of organ transplantation. Washington, DC: Catholic University of America Press.Google Scholar
  90. 90.
    Sinnott-Armstrong, Walter. 1988. Moral dilemmas. New York: Blackwell.Google Scholar
  91. 91.
    Arnolds, Edward B., and Norman F. Garland. 1974. The defense of necessity in criminal law: The right to choose the lesser evil. Journal of Criminal Law and Criminology 65: 289–301.CrossRefGoogle Scholar
  92. 92.
    Trotter, Gary T. 2002. Necessity and death: Lessons from Latimer and the case of the conjoined twins. Alberta Law Review 40: 817–840.Google Scholar
  93. 93.
    Janssens, Louis. 1979. Ontic evil and moral evil. In Readings in moral theology, Vol. 1: Moral norms and Catholic tradition, ed. Charles E. Curran and Richard A. McCormick, 40–93. Ramsey: Paulist Press.Google Scholar
  94. 94.
    R v. Dudley and Stephens, (1884) 14 QBD 273 (DC).Google Scholar
  95. 95.
    Kotecha, Birju. 2013. Necessity as a defence to murder: An Anglo-Canadian perspective. Journal of Criminal Law 78: 341–362.CrossRefGoogle Scholar
  96. 96.
    Fletcher, George P. 1974. The individualization of excusing conditions. Southern California Law Review 47: 1269–1309.Google Scholar
  97. 97.
    O’Neill, James, Jr. 2006. Conjoined twins. In Pediatric surgery, vol. 2. 6th ed, ed. Jay L. Grosfeld, James A. O’Neill Jr., Eric W. Fonkalsrud and Arnold G. Coran, 2079–2093. Philadelphia: Mosby.CrossRefGoogle Scholar
  98. 98.
    Spitz, Lewis. 2003. Surgery for conjoined twins. Annals of the Royal College of Surgeons of England 85: 230–235.CrossRefGoogle Scholar

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Authors and Affiliations

  1. 1.Philosophy DepartmentSaint Louis UniversitySaint LouisUSA

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