Biology is not necessarily destiny Dr G. Moscoso/Science Photo Library

“PRENATAL exposure to progesterone affects sexual orientation in humans”. A bold and unequivocal-sounding title for a scientific paper. And certainly important if true. But is it?

The study claimed to show that women given extra progesterone during pregnancy, routinely prescribed to prevent miscarriage, bleeding or premature delivery, have children who are “29 per cent more likely” to later identify as bisexual.

It would be a landmark finding, allowing us to also ground in biology the established social science contention that sexuality has more dimensions than straight and gay.

We suspected …