How tall is my child going to be?

About 6’3″.

What? It could happen.

The truth is, it’s impossible to know how tall a young child is going to be when they grow up. Genetics have the most important role in determining how tall a person is going to be, but there are other forces at play as well. Tufts University researcher Chao-Qiang Lai, an expert on healthy aging, writes in the Scientific American that genetics are between 60 and 80% responsible for adult height, whereas environmental factors (mostly nutrition) account for between 20 and 40%.

Best guesses

So now we know that genetics are largely responsible for determining height, but we don’t know exactly how much. Of course, just because we can’t determine the adult height of a child, doesn’t mean people won’t try, and try to pass off those guesses as fact. One common formula for predicting height looks like this:

  1. Add the mother’s height and the father’s height together in inches or centimeters
  2. Divide by two
  3. Add 2.5 inches (6.4 cm) for boys, subtract 2.5 inches for girls

And voila! Try this little formula for yourself with your parents’ heights, and ask your friends and family to do the same. Though it’s probable that your real height is close to your predicted height, this isn’t always the case. It’s entirely possible for two short parents to have a tall child, and vice versa. It’s just more likely that the child of short people will end up vertically challenged.

Environmental factors

Genetics are one (large) piece of the puzzle, but environmental factors can also have an impact on height. Popular myths state that both cigarette smoking and early weightlifting can stunt growth, but there isn’t a whole lot of evidence to back this up. There is, however, plenty of evidence that nutrition affects height. It’s clear that populations who maintain better overall nutrition (this means both getting enough calories, and getting a wide variety of the vitamins and minerals that the body needs) are taller, when all else is equal. Beyond overall nutrition though, there is some evidence that specific behaviors can have an impact.

Some studies have linked protein consumption to height. Another study, published in the American Journal of Clinical Nutrition, found that height was positively correlated with how much cow’s milk a teenager drinks. Unfortunately, it’s unclear if the positive effects were simply due to the calcium, or if cow’s milk has other height-promoting properties. Nonetheless, links between nutrition and height have been conclusively demonstrated.

The bottom line

So how tall is Baby going to be? Well, if you’re tall, and your partner is tall, Baby will probably be tall. If you’re short, and your partner is short, Baby will probably be short. If one of you is tall and the other is short, then hey, all bets are off. There’s simply no way to accurately predict the height of a child – especially one as young as Baby. Just focus on keeping him to a nutritious diet, and there’s no limit to how tall he could be.

Except for genetics. It’s mostly genetics.


Sources
  • Dr. Chao-Qiang Lai. “How much of human height is genetic and how much is due to nutrition?” ScientificAmerican. Scientific American, A Division of Nature America, Inc., Dec 11 2006. Web.
  • Jay L. Hoecker. “What’s the best way to predict a child’s adult height?” MayoClinic. Mayo Foundation for Medical Education and Research, Feb 26 2014. Web.
  • JM Perkins, SV Subramanian, G Davey Smith, E Özaltin. “Adult height, nutrition, and population health.” Nutrition Reviews. 74(3). Web. Mar 1 2016.
  • P Grasgruber, , J Cacek, T Kalina, M Sebera. “Effect of cow milk consumption on longitudinal height gain in children.” Am J Clin Nutr. 80(4)1088-1089. Web. Oct 2004.
  • Tomoo Okada. “The role of nutrition and genetics as key determinants of the positive height trend.” Economics & Human Biology. 15. 81-100. Web. Dec 2014.
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