From the 1991 Hypothalamus (Brain) Study, Simon LeVay, who self-identifies as gay, said: "It's important to stress what I didn't find. I did not prove that homosexuality is genetic, or find a genetic cause for being gay. I didn't show that gay men are born that way, the most common mistake people make in interpreting my work. Nor did I locate a gay center in the brain."2
And from the 1991 Twins Study, Richard Pillard – also a gay man – admits: "Although male and female homosexuality appear to be at least somewhat heritable, environment must also be of considerable importance in their origins." 3
And from the 1993 X Chromosome Study, Dean Hamer – also a gay man – said: "…environmental factors play a role. There is not a single master gene that makes people gay…I don’t think we will ever be able to predict who will be gay."4
And from the 2005 Fruit Fly Study, Barry dikkson, the lead researcher, admitted that the understanding of how innate behaviors are genetically determined is "rudimentary at best." He also admitted that the male-male courtship behaviors they observed probably involved "environmental and social stimuli" and that the female-female courtship behavior was abnormal – missing some key steps.5
And what about the 2005 male and 2006 female pheromone studies from Sweden that gay activists claimed were more evidence of a biological basis to homosexuality? (Pheromones are chemicals that can be smelled and are known to influence animal behavior. However, their role in humans is unknown.) Here, it is significant that Ivanka Savic, the lead researcher, said that the 2005 study had nothing to do with proving homosexuality to be biological. And regarding the 2006 study, she said "it is very important to make clear that the study has no implications for possible dynamics in sexual orientation."6
More recently, Dr. Francis Collins, head of the Human Genome Project, summed up the research on homosexuality saying that "sexual orientation is genetically influenced but not hardwired by DNA, and that whatever genes are involved represent predispositions, not predeterminations" (italics added).7
As a comparison, Collins indicates that the potential genetic component for homosexuality is much less than the genetic contribution that has been found for common personality traits such as general cognitive ability, extroversion, agreeableness, conscientiousness, neuroticism, openness, aggression and traditionalism.8