Are Large Families Really More Likely to Have All Boys or All Girls? The Surprising Science Behind It

Ever wonder if having all boys or all girls in a family is just a coin toss? For many, the idea that the chances are a perfect 50/50 split feels intuitive. But what if I told you recent research suggests otherwise? That’s exactly what a fascinating study covered by NPR uncovered: larger families tend to have a distinct leaning toward all boys or all girls, challenging our assumptions about gender odds.

Let me walk you through what this means — not just scientifically but personally — especially for those thinking about family planning, fertility, and maybe even considering at-home insemination options like the ones offered by MakeAMom.

The Study That’s Turning Heads

Researchers analyzed decades of birth records from various countries and noticed something quite unexpected: in larger families, the distribution of children’s genders wasn’t an even mix as we often assume. Instead, there was a surprising tendency for families to have all children of the same sex — either all boys or all girls — more often than pure chance would predict.

This is a big deal because it challenges the classic