Geenien rooli homoseksuaalisuuden ilmenemisessä
Kattosivustolla (NARTH) ei ole ollenkaan puhtaat jauhot pussissa, mutta Human Genome Projectin johtajan haastattelu aiheesta on mielenkiintoinen:
[size=150:erw57fhh]"Homosexuality Is Not Hardwired," Concludes Dr. Francis S. Collins, Head Of The Human Genome Project[/size:erw57fhh]
The heritability estimates for personality traits were varied: General Cognitive Ability (50%), Extroversion (54%), Agreeableness (42%), Conscientiousness (49%), Neuroticism (48%), Openness (57%), Aggression (38%) and Traditionalism (54%).
Kirk et al. (2000) in their research using a community-based cohort of Australian twins reported a heritability estimate of 30% for homosexuality. Whitehead (1999, 2006) in his extensive review of the research cites 30% as the estimate of heritability for homosexuality as well, though he views the estimate as a maximum.
Estimates of heritability are based upon careful analyses of studies conducted with identical twins. Such studies are important and lead to the conclusion that heredity is important in many of these traits. It is important however, to note that even in such studies with identical twins, that heritability is not to be confused as inevitability.
As Dr. Collins would agree, environment can influence gene expression, and free will determines the response to whatever predispositions might be present.
Dr. Collins succinctly reviewed the research on homosexuality and offers the following: "An area of particularly strong public interest is the genetic basis of homosexuality. Evidence from twin studies does in fact support the conclusion that heritable factors play a role in male homosexuality. However, the likelihood that the identical twin of a homosexual male will also be gay is about 20% (compared with 2-4 percent of males in the general population), indicating that sexual orientation is genetically influenced but not hardwired by DNA, and that whatever genes are involved represent predispositions, not predeterminations."
Dr. Collins noted that environment, particularly childhood experiences as well as the role of free will choices affect all of us in profound ways. As researchers discover increasing levels of molecular detail about inherited factors that underlie our personalities, it's critical that such data be used to illuminate, not provide support to idealogues.
Biologinen komponentti on siis ilmeisesti olemassa, mutta sen "väistämättömyys" on uusimmankin tiedon mukaan hyvin kyseenalaista.
Pretending to be certain about propositions for which no evidence is even conceivable—is both an intellectual and a moral failing. —Sam Harris