"Evolutionary geneticist R. C. Lewontin stated this explicitly in his 1984 work, "Not in Our Genes."
"Up to the present time no one has ever been able to relate any aspect of human social behavior to any particular gene or set of genes, and no one has ever suggested an experimental plan for doing so. Thus, all statements about the genetic basis of human social traits are necessarily purely speculative, no matter how positive they seem to be."
Dr. Francis S. Collins, head of The Human Genome Project, was quoted as saying, "An area of particularly strong public interest is the genetic basis of homosexuality. Evidence [indicates] that sexual orientation is genetically influenced but not hardwired by DNA, and that whatever genes are involved represent predispositions, not predeterminations."
Edward Stein, a pro-gay psychologist, explains that "Genes in themselves cannot directly specify any behavior or psychological phenomenon. Instead, genes direct a particular pattern of RNA synthesis, which in turn may influence the development of psychological dispositions and the expression of behaviors. There are many intervening pathways between a gene and a disposition or a behavior...No one has presented evidence in support of such a simple and direct link between genes and sexual orientation."
Baker, a behavioral psychologist, agrees. "Each [behavior] is affected by multiple genes interacting with multiple environmental influences...Unfortunately, many people have a different impression. They think that a gene controls a behavioral trait. This is genetic determinism, the belief that the development of an organism is determined solely by genetic factors. Genetic determinism is a false belief. It comes from misunderstandings of scientific research."
Robert Plomin, a behavioral geneticist, states, "Genes do not act as master puppeteers within us. They are chemical structures that control the production of proteins; thereby indirectly affecting behavior...Genes do not determine one's destiny."
Let me summarize. Michael Rutter, a geneticist, explains that genes specify protein synthesis; genes do not determine complex social behaviors. Byne, a physician and biologist, states that there is no evidence for a gay gene, no support for the theory that prenatal or postnatal hormone imbalance causes homosexual behavior and no proof that there are structural differences in the brains of homosexuals and heterosexuals."
Professor stands firm in 'no gay gene' theory, refutes Gifford's stance