Sexual orientation may be set by sex hormones in the uterus

Some women may be born gay because of the amounts of male and female sex hormones they were exposed to in the uterus, according to a new study.

Based on a review of 460 scientific studies, New Zealand and European researchers argue that the quantities of testosterone and oestrogen may be crucial in understanding the full range of female traits – from those that are typically masculine, to those that are typically feminine.

The researchers believe that arguments suggesting same-sex sexual behaviours are contrary to the order of nature are implausible when seen in the context of their findings.

Sex hormones play a key role in the development of reproductive organs and other characteristics. Testosterone is found in men and less so in women. Oestrogen, too, is produced in the bodies of both sexes, but plays a bigger role in women.