#maternal-age

#maternal-age

The human sex ratio has long been of interest to biologists, statisticians, demographers, sociologists, and economists. Here, we showed that within each sibship size, sex at birth did not conform with a simple binomial distribution and identified a significant intramother correlation in offspring sex.

In families with three boys, there is a 61% chance that the next sibling is male, while families with three girls have a 58% chance of another female.