Psychological Features of Human Reproductive Cloning: A Twin-Based Perspective
By Nancy L. Segal, PhD |
December 1, 2006
It is impossible to forecast every possible outcome (either positive or negative) from HRC. It is, therefore, mandatory that concerns be addressed using better models and research methods to anticipate future consequences.
Assisted reproductive technologies (ART), once a novel set of procedures that some feared would destroy the nature and structure of families, are now widely practiced. Most important, ART has allowed countless infertile couples to raise families.
Available human models are useful for sharpening thinking about issues raised by HRC. Paradigms presented by Levick are exemplary in this respect, but have yielded considerable speculation (mostly negative), in the absence of empirical data.30 A quote from his book is illustrative: "a child too dissimilar to a narcissistic parent may find his dissimilarity quite detrimental. However, resemblance may carry its own problems, enhancing parental expectations that the child will be like the parent. Such is apt to be the plight of a self-clone." (p. 95).
Assessing these alternative outcomes could be accomplished by detailed longitudinal studies of unusually similar and dissimilar parent-child and sibling pairs. A televised segment of 4 very similar looking mother-daughter pairs underlined the pleasure they gained from their shared qualities and interests. Exceptions to this outcome may be expected, but knowing that similarity does not imply dissatisfaction—and may enhance satisfaction—is central to this debate.
There is a near-exclusive focus by Levick on negative motivations, mostly narcissism, with respect to parents choosing to clone.31 No doubt, there are also ordinary biological parents who have children for less than admirable reasons—to keep their marriage together, to continue the family business, to have caretakers in old age. Perhaps an infertile couple would clone a son or daughter simply out of love for a child.
In conclusion, based on my research experience with MZ twins and the experiences of other investigators, a number of concerns about HRC's potential psychological costs appear to be of less consequence than generally presumed. At the same time, several benefits seem likely. It is important to note, however, that even if some issues can be resolved and some benefits found, this would not necessarily justify the procedure—just additional dialogue and discussion.
Dr Segal is professor of psychology at California State University, Fullerton, and director of the Twin Studies Center there. She is the author of 2 books on twins: Entwined Lives: Twins and What They Tell Us About Human Behavior (Plume, 2000) and Indivisible by Two: Lives of Extraordinary Twins (Harvard University Press, 2005). She reports no conflicts of interest concerning the subject matter of this article.
- Segal NL. Behavioral aspects of intergenerational cloning: what twins tell us. Jurim. 1997;38:57-67.
- Segal NL. Indivisible by Two: Lives of Extraordinary Twins. Cambridge, Mass: Harvard University Press; 2005.
1. Vogel G. Cloning: Could humans be next? Science. 2001;291:808-809.
2. Robertson JA. Wrongful life, federalism, and procreative liberty: A critique of the NBAC Cloning Report.
3. Segal NL. Human cloning: A twin-research perspective. Hastings Law J. 2002;53:1073-1084.
4. Wilmut I, Highfield R. After Dolly: The Uses and Misuses of Human Cloning. New York: Norton; 2006.
5. Macintosh KL. Illegal Beings: Human Clones and the Law. Cambridge, England: Cambridge University Press; 2005.
6. Nussbaum MC, Sunstein CR. Clones and Clones. New York: WW Norton; 1998.
7. Symposium: Conceiving a Code for Creation: The Legal Debate Surrounding Human Cloning. Presented at: Hastings Law School; January 26, 2002; San Francisco.
8. Stolberg SG. Total ban on cloning research appears dead. The New York Times. June 14, 2002:A31.
9. Park A. The perils of cloning. Time Magazine. July 10, 2006;188:56-58.
10. The Clone Age [television production]. Studio City, Calif: Pie Town Productions; 1987.
11. National Bioethics Advisory Commission. Cloning human beings. Rockville, Md: NBAC; 1997.
12. Encarta World English Dictionary. 2006. Available at: http://encarta.msn.com/encnet/features/dictionary/
dictionaryhome.aspx. Accessed November 3, 2006.
13. Segal NL. Entwined Lives: Twins and What They Tell Us About Human Behavior. New York: Plume; 2000.
14. Machin GA, Keith LG. An Atlas of Multiple Pregnancy. New York: Parthenon;1999.
15. Malik K. The moral clone. Prospect. 2001;63:10-11.
16. Segal NL, Johnson W. Twin studies of general mental ability. In: Kim Y-K, ed. Handbook of Behavior Genetics. New York: Springer. In press.
17. Segal NL. Indivisible by Two: Lives of Extraordinary Twins. Cambridge, Mass: Harvard University Press; 2005.
18. Bouchard TJ Jr, Lykken DT, McGue M, et al. Sources of human psychological differences: The Minnesota Study of Twins Reared Apart. Science. 1990;250:223-228.
19. Plomin R, DeFries JC, McClearn GE, McGuffin P. Behavioral Genetics. 4th ed. New York: Worth; 2001.
20. Silver L. Public policy crafted in response to public ignorance is bad public policy. Hastings Law J. 2002;
21. Shields J. Monozygotic twins: Brought Up Apart and Brought Up Together. London: Oxford; 1962.
22. Claridge G, Canter S, Hume WI. Personality Differences and Biological Variations: A Study of Twins. Oxford, England: Pergamon; 1973.
23. Tellegen A, Lykken DT, Bouchard TJ Jr, et al. Personality similarity in twins reared apart and together. J Pers Soc. Psych. 1988;54:1031-1039.
24. Coccaro EF, Bergeman CS, McClearn GE. Heritability of irritable impulsiveness: a study of twins reared apart and together. J Psych Res. 1993;48:29-242.
25. Kendler KS, Martin NG, Heath AC, Eaves LJ. Self-report psychiatric symptoms in twins and their nontwin relatives: are twins different? Am J Med Gen. 1995;18:588-591.
26. Tomassini C, Juel K, Holm NV, et al. Risk of suicide in twins. BMJ. 2003;327:373-374.
27. Segal N, Hershberger SL, Arad S. Meeting one's twin: perceived social closeness and familiarity. Evol Psych. 2003;1:70-95.
28. Tancredy CM, Fraley RC. The nature of adult twin relationships: an attachment-theoretical perspective.
J Pers Soc Psych. 2006;90:78-93.
29. Foy AK, Vernon PA, Jang K. Examining the dimensions of intimacy in twin and peer relationships. Twin Res. 2001;4:443-452.
30. Neyer FJ. Twin relationships in old age: a development perspective. J Pers Soc Rel. 2002;19:155-177.
31. Prainsack B, Spector T. Twins: a cloning experience. Soc Sci Med. 2006;63:2739-2752.
32. Levick SE. Clone Being: Exploring the Psychological and Social Dimensions. Edinburgh: Rowman & Littlefield; 2004.