Fit Females Make More Daughters; Mighty Males Get Grandsons

If a woman has more sons than daughters, it might not be just because of chance. Research at the University of Exeter (U.K.), Okayama University and Kyushu University (Japan) shows that weaker females, whose own fathers were stronger and more successful, produce more sons.

The scientists found that females may influence the gender of their offspring so that they inherit either their mother’s or grandfather’s qualities.

While this research focuses on the broad-horned flour beetle, Gnatocerus cornutus, the researchers believe the findings could apply to other species across the animal kingdom, even mammals.

Researcher David Hosken of the University of Exeter says: “Our study shows females are able to bias the sex ratio of their offspring in surprising and subtle ways. These findings shed new light on why some families have lots of sons, while others have mainly daughters. Of course everyone will be interested to know if the study can help explain why this sometimes happens in human families but I’m afraid we can’t answer that!”