An interesting and important piece from Discovery magazine.
“Are people born gay or is it a choice? A new study of gay brothers, the largest to date, adds more scientific evidence that there’s a genetic basis for homosexuality.
A genetic analysis of over 409 pairs of gay brothers found that two areas of the human genome, a portion of the X chromosome and a portion of chromosome 8, were associated with the men’s sexual orientation. The findings gel with a smaller study conducted in 1993 that implicated the same area of the X chromosome.”
You can read the rest of the article at Discovery magazine.
So why is this important for research on gender dysphoria?
1) If sexual orientation is influenced by genes, then researchers looking for genes related to gender identity need to control for sexual orientation.
Trans men (born female) are usually attracted to women and about half of trans women (born male) are attracted to men, so they might share genes with cis lesbians or gay men.
Future studies of genes and gender dysphoria need to include cis gay men and lesbians in the control groups.
2) The genes that may be involved in male homosexual orientation were found on the X chromosome and chromosome 8. The researchers looked at the whole genome for 409 pairs of homosexual brothers.
Studies of genes for gender dysphoria have focused on genes known to be related to sex hormones and the X and Y chromosomes (read more in Genes and Gender Dysphoria). This makes sense if you are looking at behavior that is related to sex differences, but perhaps the genes are somewhere else.
So far, researchers have had not luck finding genes related to gender dysphoria in trans women and only some luck finding genes related to gender dysphoria in trans men. Perhaps the genes for gender dysphoria and the mechanism involved are not what we expect.
A whole genome scan for genes related to gender dysphoria would be a great study for someone to do.