Predicting height from genes

How well can you predict height based on genetic markers?

A 2009 study came up with a technique for predicting the height of a person based on looking at the 54 genes found to be correlated with height in 5,748 people — and discovered the results were one-tenth as accurate as the 125–year-old technique of averaging the heights of both parents and adjusting for sex.

The quote above is from Wrong: Why experts keep failing us — and how to know when not to trust them by David Freedman.

The article Freedman quotes is Predicting human height by Victorian and genomic methods. The “Victorian” method is the method suggested by Sir Francis Galton of averaging parents’ heights. The article’s abstract opines

For highly heritable traits such as height, we conclude that in applications in which parental phenotypic information is available (eg, medicine), the Victorian Galton’s method will long stay unsurpassed, in terms of both discriminative accuracy and costs.

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4 thoughts on “Predicting height from genes

  1. Why are we predicting heights to begin with? Why not just wait until the baby’s grown and measure it? I’m sure that predates the Victorians and has pretty much perfect predictive accuracy.

    Seriously, though, what if we only have a baby and don’t know the parents? Does the genetic method beat guessing the average height for gender? If so, I think there’s content to the analysis even if there are better predictive methods if more is known.

    Or, if we really care about prediction, we could add paternity and maternity tests, choosing the Victorian or genetic method based on their outcome.

    We could probably also reduce the overall variance by combining the two predictors, parents’ height and genome.

  2. To me, the significance of the study is that predicting a simple, familiar outcome such as height from genetic information is apparently very hard. And that implies predicting complex, unfamiliar outcomes may be even harder.

    Think how many researchers are interested in height compared to how many researchers are interested in the effectiveness of a particular compound in treating a particular kind of cancer.

    Now it may be that predicting height from genes is hard because the information simply isn’t in the genes. Maybe environment plays a larger role than expected. But the same misgivings apply to cancer research: maybe genes don’t hold the answers to the questions we’re asking of them.

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