Is it more likely for brothers and sisters to be gay
However, the researchers think their findings are linked to what happens in the womb, rather than the effects of growing up among older boys. For decades, academics have argued over nature versus nurture - whether individuals are born gay, or become gay because of where and how they grow up. Now Canadian psychologist Ray Blanchard says the answer depends on how many older brothers a man has. He studied the family backgrounds of gay men and the same number of straight men.
We may know why younger brothers are more likely to be gay
Brothers and Sisters of Gays and Lesbians | Psychology Today
By Andy Coghlan. Anthony Bogaert at Brock University, Canada, and his team think that some women who are pregnant with boys develop antibodies that target a protein made by the Y chromosome. Our immune systems make antibodies to recognise foreign molecules, which have the potential to be from dangerous bacteria. But pregnant women sometimes also produce antibodies against fetal molecules — for example, if their fetus has a different blood group. The team collected blood from women, and screened it for antibodies to a particular brain protein that is only made in males. They thought this would be a good candidate, because it plays an important role in how neurons communicate with each other, and because it is produced on the surface of brain cells, making it relatively easy for antibodies to find and detect it. They found that the mothers of gay sons with older brothers had the highest levels of antibodies against this protein, followed by the mothers of gay sons with no older brothers.
Boys with big brothers more likely to be gay
Between 2 and 11 percent of human adults report experiencing some homosexual feelings, though the figure varies widely depending on the survey. Homosexuality exists across cultures and even throughout the animal kingdom, as the authors of a mammoth new review paper on homosexuality write. Between 6 and 10 percent of rams prefer to mount other rams, not ewes.
Here's how to inoculate ourselves against negative ones. Verified by Psychology Today. Gay and Lesbian Well-Being. What is it like to have a sibling who is gay or lesbian?