From "Homosexuality Is Not Hardwired," Concludes Head of The Human Genome Project" by A. Dean Byrd, posted 3/20/07 at Lifesite.net
Reprinted with permission of the National Association for Research and Therapy of Homosexuality (NARTH)
Francis S. Collins, one of the world's leading scientists who works at the cutting edge of DNA research, concluded that "there is an inescapable component of heritability to many human behavioral traits." However, he adds, "for virtually none of them, is heredity ever close to predictive."
In reviewing the heritability (i.e., influence of genetic factors) on personality traits, Dr. Collins referenced the research of Bochard and McGue for the estimated percentage of these traits that can be ascribed to heredity.
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%).
Such estimates of heritability are based upon unbiased, careful analyses of studies conducted with identical twins. The studies lead to the conclusion that heredity is important in many of these personality 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 [emphasis added]."
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