Some Interesting Facts

There is an article in the Huffington Post about a genetic link to homosexuality that it tends to run in families, I don’t think that surprises anyone.

New Study Suggests Genetic Link For Male Homosexuality
AP
By Lindsey Tanner
Posted: 11/17/2014

CHICAGO (AP) — A large study of gay brothers adds to evidence that genes influence men's chances of being homosexual, but the results aren't strong enough to prove it.

Some scientists believe several genes might affect sexual orientation. Researchers who led the new study of nearly 800 gay brothers say their results bolster previous evidence pointing to genes on the X chromosome.

They also found evidence of influence from a gene or genes on a different chromosome. But the study doesn't identify which of hundreds of genes located in either place might be involved.

There are also studies that show birth order and age of parents at the time of conception also contributes to factors homosexuality. WebMD has an article about birth order,

Men may be more likely to be homosexual if they share their birth mother with older brothers, even if they didn't grow up with those brothers.

"These results strongly suggest a prenatal origin to the fraternal birth-order effect," writes Canada's Anthony Bogaert, PhD, in the early online edition of Proceedings of the National Academy of Sciences.
[…]
"Only biological older brothers, and not any other sibling characteristic, including nonbiological older brothers, predicted men's sexual orientation, regardless of the amount of time reared with these siblings," writes Bogaert.

Bogaert's findings don't prove that birth order determines sexual orientation. However, Bogaert writes that the study supports the idea that sexual orientation starts before birth.

Another interesting finding is that gays and lesbians are more likely to be left handed, a BBC Science article about a study by Richard A Lippa and our friend (sic) Ray Blanchard said,

Recent studies have documented that gay men and lesbians are more likely to be left-handed (or ambidextrous) than heterosexuals are. Also, gay men are more likely to have an excess of older brothers, compared to heterosexual men—a phenomenon termed 'the fraternal birth order effect'. The most recent studies that look at both factors at the same time suggest that the fraternal birth order effect is true for right-handed gay men but not for left-handed gay men – that is, older brothers increase a man's odds of being gay only for right-handers.
[…]
More gay men than heterosexual men reported being left-handed (13% versus 11%). Similarly, more lesbian women than heterosexual women reported being left-handed (11% versus 10%).

There have been also some studies that gender identity is also affected by birth order and also runs in families.

The thing to remember that there is probably no one reason a person is LGBT, it is probably a very complex process. That is they ever do find a “gay gene” it will not mean that everyone has to have the gene or conversely if you have the gene you have to be LGBT. It probably a mixture of genetic, prenatal, and environmental factors that contribute to gender identity and sexual orientation.