Lesbianism is indeed at least 25 percent genetic, as determined by a 2011 study of twins conducted in the United Kingdom. The study found that identical twin sisters (who share 100 percent of their DNA) are more likely to both be lesbians than are fraternal twin sisters (who share just 50 percent), proving that, all other environmental factors being equal, genes matter.
A female’s sexual orientation also appears to be partly influenced by her level of exposure to the male sex hormone androgen when she is in the womb. Greater hormone exposure correlates with more gender nonconformity early in her life, as well as a same-sex orientation later on.
Adding to the confusion about what causes lesbianism is the slipperiness of female sexuality itself. Unlike men, who are usually sexually oriented solely toward men or women, and whose sexuality is essentially fixed from puberty on, a decade of research by the University of Utah psychologist Lisa Diamond and others demonstrates that women have greater “erotic plasticity.”
Their sexual orientation can be shaped by cultural influences, altered by positive or negative experiences and intensified by feelings of love or attachment. Women are far more likely than men to report remarkably late and abrupt onset of same-sex sexuality, often after heterosexual marriage.
Their sexual fluidity may emerge from the fact that, across the board, women are sexually aroused by images of both men and women (while men are typically only aroused by members of their preferred sex).
Therefore, the question “why are there gay women?” may be better worded as “why is female sexuality so fluid?”
Source: Live Science
Why So Few Lesbians?
Although research reveals more women than men identify as a sexual minority, it also documents that only a small proportion of these women, perhaps no more than 1% of women in the general population, identify as lesbian.
In her research over the past several decades, Dr. Lisa Diamond has also pondered this issue, leading her to conclude, “Completely exclusive same-sex attractions are less common in women than men.
Women are rarely encouraged to masturbate or to experiment sexually, not only because of sexual norms in the Western world, but because of the universal risk of pregnancy and the value placed on virginity. So women don’t grow up prioritizing their sexual impulses and feelings the way that men do, and they learn to base their sexual response on the response of the partner.
Thus, women who have an exclusive same-sex orientation are “set up by culture to remain open to attractions to men” and to those they are emotionally close to.
Maybe in humans, females just happen to be the more bisexual sex; it might make sense for females to be more ‘arousable’ to a wide range of stimuli. Then the weird thing that requires explanation is not the lack of lesbians but the exclusive, monosexual attractions of men, straight and gay.
Few of us are surprised by the low number of lesbians because, as Dr. Wallen wrote, it is what one would expect if the sexual arousal system in women is more fluid.
Source: Psychology Today