Xjyuk

German media has reported that a village in Poland has had only girls born for the last decade:

The head of the parish promises a reward, the Catholic village priest asks for God's help: In the Polish village of 300 souls, Mistitz, no boys have been born for almost ten years.

Source: "Mistitz in Polen – Dorf ohne Jungen", tagesschau Stand: 17.08.2019 11:43

How is that possible that there are no boys born? Statistically, it seems to me to be nearly impossible. Is this real, or is it a publicity gag or something else?

English media has also reported on the village: "Girls only: Tiny Polish village of 300 people waits for first birth of a boy for nearly a DECADE", Daily Mail

It's not that surprising. The village is small (current population 272, according to the New York Times), and therefore there have only been a small number of births in the last decade. The New York Post writes that

According to birth records, there hasn’t been a boy born there since 2009, though 12 girls have come into the world in that time frame.

If the chance of a baby being a boy and the chance of a baby being a girl are equal, then the odds of 12 consecutive births all yielding girls is (1/2)¹² = 0.0244%. That's small, but when you consider that there are many towns and villages in the world, it shouldn't be surprising that at some point, just from randomness, 12 girls are born in a row in a given town. The odds of the same thing happening with 12 boys (which would also be widely reported) are identical, so the odds of 12 consecutive babies having the same sex is 0.0488%. (The Daily Mail notes that in 2017, 207,000 boys were born in Poland, as were 196,000 girls, making the odds slightly lower.)

Of course, more than randomness could be at play; environmental or cultural factors could be responsible. The same New York Times article notes that

a retired doctor from central Poland . . . said that a baby’s sex depended on the woman’s diet, which should be rich in calcium if she wants to have a boy.

which implies that some sort of calcium deficiency could be responsible. While I can't speak to the effect of calcium in determining a baby's sex, and haven't found any evidence to support the claim, it's possible that maternal diet pre-conception (not post-conception, of course) can play a role. Several studies have claimed that the sex of a child can slightly be influenced by dietary factors:

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  Breakfast cereals, salt and potassium may increase the chances of having a boy (Mathews 2008))


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  A maternal high-fat diet may lead to more male offspring in mice (Mao et al. 2010)

I would like to note that these results, and others like them, only indicate that there may be some relationships between diet and the sex of a baby (and the latter study is only about mice!). I include them only to point out that if the people of Mistitz have an abnormal diet, this may affect their odds of producing baby boys. The Daily Mail article above mentions that scientists "have offered to conduct research to investigate the unique situation", and perhaps any environmental factors will be turned up if that research happens.