Playing Favorites

From MailOnline:

Grandparents can't help having favourites - they prefer the grandchildren with whom they share the most DNA, research suggests.

The phenomenon explains studies that have shown a paternal grandmother benefits her granddaughters' health more than grandsons.

This is because a woman passes around 31 per cent of her genes to her son's daughters but just 23 per cent to her son's sons - suggesting a protective effect for the grandchildren they are most closely related to.

The article also helpfully adds:

A woman always knows she is the mother of her child but a man has some uncertainty about his paternity because he might have been cuckolded.

Read more here.

MR