In the village of Miejsce Odrzanskie in Poland, every single newborn has been a girl for nearly 10 years – not one single baby boy in almost a decade.
This curious case caught the eye of the media this month, with reports on the village popping up everywhere from local Polish media to The New York Times. The small village, found in the rural south of Poland near the Czechia border, has a population of just over 300 people. Over the past decade, there have been 12 births and not one boy has been born. Rajmund Frischko, the local mayor and the father of two daughters, even offered a prize for the first family to conceive a boy.
“There has been so much talk about us in the media that for a minute there I was considering naming a street after the next boy born here,” he told The Telegraph. “He will definitely get a very nice gift. And we will plant an oak and name it after him.”
So, what could possibly be going on here?
The sex of a baby depends on whether their father’s sperm is carrying an X or Y chromosome. An X chromosome combines with the mother’s X chromosome to make a baby girl (XX) and a Y chromosome will combine with the mother’s X chromosome to make a boy (XY). The number of X and Y sperms is roughly equal, so the chances of having a boy or a girl are roughly equal too.
That’s in theory, at least. There are a small handful of factors that can shift the proportion of X and Y sperms or number of boys and girls. For example, men inherit a slight tendency to have more X or Y sperms from their parents. The X chromosome is also longer and heavier than the Y chromosome, so it’s ever so slightly harder for the X sperms to reach the egg in the race up the fallopian tubes. The diet of the mother might also play a role.
Scientists have reportedly shown interest in the town, but so far, there’s been no hard research into the inhabitants' genetics. While it’s too early to jump to any conclusions, some of the factors above could be playing a role in the unusual trend.
However, it’s possible that this could just be a statistical coincidence. Craig Anderson, a lecturer in statistics at the University of Glasgow, explains in an article for The Conversation that Miejsce Odrzanskie’s situation isn’t actually as bizarre as it first sounds.
If we assume there’s a roughly 50-50 chance of having a boy or girl, he estimates that the probability of 12 consecutive girls being born in Miejsce Odrzanskie is 1/4096. That’s a fairly slim chance in isolation, however, in reality, any sequence of boy-girl is just as unlikely. The likelihood of 12 out of 12 births being girls might be 1/4096 in Miejsce Odrzanskie, but there's also only a 1/4096 chance that the newborns would run in a boy-girl-boy-girl sequence, or any sequence for that matter (if we assume there’s a 50-50 chance of having a boy or girl).
Human brains are really bad at computing the idea of randomness and probabilistic paradoxes. If we spot a coincidence, we have a strong tendency to dig out significance even when there is none there.