FREEMARTINS are well known to cattle farmers – they are cows that grow up sterile, the result of sharing their mother’s uterus with a male twin. Now a similar though less drastic effect has been found in humans. In what could be characterised as an example of women being suppressed by men before they are even born, girls with twin brothers have a lower chance of marrying and having children than do singletons.
Virpi Lummaa and colleagues from the University of Sheffield, UK, wanted a source of data on births, deaths and marriages from the pre-industrial era, in order to exclude…
