The Merck Manual, Sixteenth Edition, ©1992 “…The causes of homosexuality are not known and are probably as complex as the causes of heterosexuality. Constitutional factors involving hormonal programming of the brain during fetal life may be a factor. Some support for this hypothesis is to be found in the higher-than-expected prevalence of homosexual fantasies and behavior in women whose mothers received diethylstilbestrol (DES) during pregnancy…”
Interesting. I didn't know that they knew about a link between DES and homosexuality that far back. There is also a well-established link between DES and trans offspring. Both links are suspected of being causal, but of course that would require full knowledge of the neural and pharmacological pathways involved. As an anecdotal example, in my family, we believe our mother probably used DES (unknowable now, but the circumstances were right for it to have been prescribed) and, of three siblings, one is gay and one is trans.
DES is also known to be a factor in cancer in children of mothers who were prescribed DES. Long before DES was invented, homosexuals were in existence. Some claim it's a "choice" one makes. I don't buy that at ALL. I'm hetero, and I never once considered dating - or was even attracted to - the same sex. I didn't ponder it - I wasn't thinking girls or guys? ....... girls or guys? - I was just attracted to women. I think people are hard-wired how they're hard-wired. If outside chemicals play a role these days - I have no idea.