Age Of Parents Can Affect Sex Of Children, Study Finds

During and shortly after periods of war or other hardship, the number of baby boys born tends to outnumber the number of baby girls.

One possible explanation for this phenomenon is that women may tend to marry older men during these times because there’s a dearth of younger men or the women’s concerns about their well-being drive them to find men with more resources.

To try to examine whether, in fact, the age difference between a man and a woman can affect the sex of their children, evolutionary biologist John Manning of the University of Liverpool in England and his colleagues studied birth records of 301 British families, analyzing the age of the parents and the sex of their children.

Couples in which the men were significantly older than their wives were indeed more likely to have sons as their firstborn, the researchers found.