They are reflected in our psychology and the ways we relate to others. There is clearly something non-genetic going on. Heritability is not about a person; heritability is always about a population. Further evidence comes from genetic males who, through accidents, or being born without peniseswere subjected to sex change and raised as girls. Twin studies additionally point to genetic explanations as the underlying force for same-sex partner preference in men and neuroticisma personality trait that is comparable to anxiety.
Combined with environmental influences, it will be hard to detect individual genes.
Born this way? An evolutionary view of ‘gay genes’
I n a recent Guardian articleSimon Copland argued that it is very unlikely people are born gay or presumably any other sexual orientation. Combined with environmental influences, it will be hard to detect individual genes. In Western cultures, they would be considered gay men and transgender women, respectively. We can detect genetic variants that produce differences between people by tracking traits in families that display differences. So showing evidence of change is not an argument against biology.
And in fact, the heritability of bisexuality might be greater than the heritability of same-sex sexuality. For example patterns of brain organisation appear similar between gay men and heterosexual women and between lesbian women and heterosexual men. The causes of a trait should not influence how we see it. Quantitative traits, such as height, are affected by many different genes, as well as environmental factors. Differences in brain organisation mean differences in psychology and study after study show differences in cognition between heterosexual and gay people.