Women with a twin brother may be 25 percent less likely to have children than women with a twin sister, says a UK study that examined centuries-old Finnish medical records, BBC News reported.
Exposure in the womb to the male hormone testosterone may be an important factor, said Sheffield University researchers. Their study appears in the journal Proceedings of the National Academy of Sciences.
The study also found that females with a twin brother were 15 percent less likely to marry than women with a twin sister, BBC News reported.
The researchers said they analysed data on twins in the 1700s and 1800s because advanced healthcare and modern fertility/conception treatments would skew modern data.
"There is some evidence to support this observation. Exposure to testosterone in the womb in sheep recreates a similar syndrome to a condition called PCOS, which is a known cause of infertility in humans," Dr Laurence Shaw, a fertility expert at the London Bridge Fertility Centre and a spokesman for the British Fertility Society, told BBC News. – (HealthDayNews)
Taller women have twins