Why do some moms have more boys than girls—or vice versa? New study provides clues

Saturday, July 19, 2025 - 13:26 in Psychology & Sociology

At first glance, the sex of your unborn child seems like it should be a coin toss: Most sperm carry either an X or a Y chromosome, giving the baby a roughly one-in-two chance of being biologically male or female. But some families are lopsided. Reality TV star Kris Jenner, for instance, has five daughters and one son; former Spice Girl Victoria Beckham has three sons and one daughter. A study published today in Science Advances suggests that, far from a “coin toss,” some mothers may be biologically biased toward having children of one sex or another , with the effect seemingly increasing with age of first pregnancy and the number of children they...

Read the whole article on

More from

Latest Science Newsletter

Get the latest and most popular science news articles of the week in your Inbox! It's free!

Check out our next project, Biology.Net