A twin brother can reduce his female twin's chances of having children, say scientists at Sheffield University.
Women were 25% less likely to have children if their twin was male, the study, in Proceedings of the National Academy of Sciences, concluded.
Although other factors could play a part - the women were less likely to marry - the team blamed exposure in the womb to the male hormone testosterone.
Experts have agreed testosterone might potentially damage female fertility.
They said animal work supported this.
But they said more work was needed to look at human mechanisms.
http://news.bbc.co.uk/2/hi/health/6755747.stm
Talk about male oppression!
Women were 25% less likely to have children if their twin was male, the study, in Proceedings of the National Academy of Sciences, concluded.
Although other factors could play a part - the women were less likely to marry - the team blamed exposure in the womb to the male hormone testosterone.
Experts have agreed testosterone might potentially damage female fertility.
They said animal work supported this.
But they said more work was needed to look at human mechanisms.
http://news.bbc.co.uk/2/hi/health/6755747.stm
Talk about male oppression!