The Science of Sexual Orientation: What Makes Someone Gay?

Sexual orientation, according to the American Psychological Association, is an “enduring, romantic, or sexual attraction that one feels toward men, toward women or toward both.” The term is generally structured into the following: heterosexual (attraction to the opposite sex), homosexual (attraction to the same sex), and bisexual (attraction to both sexes).

Having said that, it’s important to note that sexual orientation is not the same thing as sexual activity. Adults and adolescents may identify themselves as gay, lesbian or bisexual without having shared any sexual experiences with the same sex; likewise, people may also have sexual relations with the same sex without considering themselves to be gay, lesbian, or bisexual.

There is also a difference between sexual orientation and gender identity; while the former refers to an attraction to another person, the latter pertains to the person’s internal sense of being male, female, or something else, such as trans or non-binary.

So what is it exactly that makes a person gay—is there something scientific going on?

Boiling sexual orientation down to a science

There have been a number of studies showing that sexual orientation has a biological basis—that people who are attracted to the same sex develop their orientation before they are even born, and that it is not a choice.

Here’s a brief look at the key research on the subject:

• The 1991 book “Gay, Straight, and the Reason Why: The Science of Sexual Orientation” by Simon LeVay favours the concept that hormone levels have a great impact on whether fetuses would grow to become straight, gay or bisexual adults. He proposed that female fetuses exposed to higher testosterone levels in the womb have a higher likelihood of being gay, while male fetuses exposed to lower testosterone levels, or higher androgen levels, are more likely to be gay.

LeVay points out that there may be more than a single way for a person to be gay.

Another idea he supports is that society has a clear picture of the differences in traits between men and women, and it’s been observed that gay people’s traits are typically gender shifted toward the other gender (e.g., gay men will display or demonstrate finger length ratios or trunk-to-body-length ratios, or spatial and verbal abilities, traditionally observed in women).

• A report released by the Academy of Science South Africa confirmed the association between same-sex orientation among males and a specific chromosomal region. The evidence from the study points to the existence of an interaction between the environment and a person’s genes, which means that the environment can be responsible for sexual orientation’s heritable nature.

• A study involving more than 400 pairs of gay brothers, published in the Psychological Medicine Journal in 2014, revealed that a gene on the sex chromosome X called Xq28, and a gene on chromosome 8, are found in higher prevalence among gay men. While this does not yet point to the existence of a specific “gay gene,” it does reveal the presence of genes that result in a higher likelihood of being gay.

• Research by evolutionary geneticist William Rice reinforces the lack of a “gay gene,” and instead suggests that a process called epigenetics can explain why homosexuality runs in families and thus persists in nature even though gay people are less likely to reproduce. Rather than passing down traits through genes, epigenetic change occurs in the manner that the genes are turned on or off, or regulated.

There is still much that needs to be discovered and understood about sexual orientation and gender identity, and these findings can only be reached through continued research and a commitment to learning more about sex, the self, and society in relation to one another.

Are you an LGBTQI+ person who is struggling in your life or relationships?

If so, contact Sydney Gay Counselling on  (02) 8968 9323 to find out how we can help or book an appointment online.