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When you imagine having a baby, you might hope for a boy, a girl, a healthy baby, or in a perfect world, at least one of each. After all, it\u2019s a 50\/50 shot, right?<\/p>\n
It turns out that, like a coin flip, that\u2019s not exactly true \u2013 and as a mom who had four pregnancies, all boys, I can certainly attest to that fact.<\/p>\n
Now, researchers believe they may have isolated some genetic factors that contribute to couples having all one gender or the other.<\/p>\n
The team of researchers, out of the Harvard T.H. Chan School of Public Health, say that gender determination is about more than chromosomes, and it turns out that their data supports the general idea that there are many couples out there having children that are all one gender.<\/p>\n
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They analyzed data that included 58,007 women who were part of the Nurses\u2019 Health Study and found that there were more families with all one gender siblings than there would be with a simple 50\/50 split.<\/p>\n
One thing they believe could influence these odds are the age of the mother. They found that when a woman\u2019s first pregnancy is later in life, she is more likely to give birth to a single gender.<\/p>\n
They also found that families that had more than three children were more likely to only have one gender.<\/p>\n
When the researchers dug into the genomes of these women, they did come up with some potential genetic factors as well. Specifically, they identified three genes \u2013 CYP2U1, NSUN6, and TSHZ1 \u2013\u00a0that seem to be associated with this phenomenon.<\/p>\n
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These trends held up even when the researchers removed the final child in each family from the equation in an attempt to control for people who continued having babies until they got one of the opposite gender.<\/p>\n