Studies Show Birth Month Can Affect Genetic Traits

Different Seasons

When you’re pregnant, it’s hard to resist anything that says it can predict what kind of child you’ll end up with. After those ubiquitous due date calculators (which are only accurate 5 percent of the time anyway), there are astrology charts, ancient Chinese gender charts, studies about how birth order affects personality, and plenty of old wives’ tales, including that rhyme about how the day of birth relates to a child’s temperament.

Monday’s child is fair of face

Tuesday’s child is full of grace,

Wednesday’s child is full of woe.

Thursday’s child has far to go,

Friday’s child is loving and giving,

Saturday’s child works hard for a living,

But the child who is born on the Sabbath Day

Is bonny and blithe and good and gay.

It seems silly to think that when a baby is born has anything to do with what kind of person he or she will turn out to be, right? Well, now there might be some science to back it up. This article from Monday’s “Los Angeles Times” collects research from hundreds of studies all suggesting that the month or season during which a baby is born can affect dozens of characteristics – everything from height, weight, life span, sleep habits, likelihood of developing certain diseases, and yes, even personality.

According to these studies, certain seasonal traits like temperature, exposure to sunshine, access to particular seasonal foods and bouts of winter infections can all influence the development of a fetus. Some of the claims make sense – I can see how a vitamin D deficiency in winter-born babies could lead to allergies – but for the most part I’m not sure I buy a lot of it. Just look at identical twins: they’re as similar as two people can get genetically, but do they end up with the same traits just because they were born during the same season? No.

According to some of the studies cited, my baby, due in July, is more likely to be left-handed, a night owl, and have an increased risk of Type 1 diabetes. And according to the rhyme at the beginning of this post, if s/he’s born on her due date – a Wednesday – those might be the least of my problems.

What do you think about the research? Should I run right out and buy some lefty scissors for my unborn July baby? I’m not convinced. Do any of the study results ring true for your children, or even yourself or other people you know? Are you paying attention to the science – or the astrology – of seasonal birth when it comes to your soon-to-be?