Wednesday, October 14, 2009

Version 2.0 of Montana & Gretzky   posted by Razib @ 10/14/2009 05:09:00 PM

Since we're talking about athletics & heritability, California School Has a Montana and a Gretzky at Quarterback. Unfortunately regression toward the mean implies you'd have to bet against the sons of some of the greatest players in professional sports having anything close to the same impact. On the other hand, having a professional athlete parent is going to increase your odds of being a successful athlete in the pros by orders of magnitude I suspect. The expectation is that children of professional athletes, who are many standard deviations above the norm, will regress back toward the mean as a function of heritability. But the expectation of their athleticism is going to be far higher than the norm, and because there is going be variance around that expectation it also increases the probability that those children will match their parent, or even outperform them. The Manning brothers and Barry Bonds are cases where the offspring are more exceptional than their parent.

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Tuesday, October 13, 2009

There are no NFL genes (?)   posted by Razib @ 10/13/2009 01:34:00 PM

23andMe performs genome-wide association study on NFL players, fails to find athlete genes:
It's unsurprising that the results of this study are negative (more on this below), but the conclusions they draw from this are fallacious. In fact we know from twin and family studies that many (but not all) traits related to athletic performance are highly heritable; researchers just haven't been able to track down the vast majority of the genetic variants responsible yet, and this study is no exception.

What 23andMe have actually shown here is that the limited subset of genetic variation captured by their genotyping chip (which almost exclusively targets genetic variants with a frequency of greater than 5%) doesn't include any variants with an extremely strong association with NFL prowess.

That shouldn't come as a surprise to anyone who's been following advances in human genetics for the last few years; a genome-wide association study on a highly complex trait with a sample size of 100 has, historically speaking, a vanishingly small chance of yielding any positive results at all. (Yes, there are exceptions, but I don't think a sensible prior expectation would be that athletic performance has a similar genetic architecture to macular degeneration.)

NFL players are taller and heavier than average, in addition to being able to run the 40 in 4.5 seconds. Seems like a lot of these are quantitative traits.

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