By Bryan Caplan
Steven Pinker answered the call to “know thyself” by having his genome sequenced. Some results:
The two biggest pieces of news I got about my disease risks were a 12.6 percent chance of getting prostate cancer before I turn 80 compared with the average risk for white men of 17.8 percent, and a 26.8 percent chance of getting Type 2 diabetes
compared with the average risk of 21.9 percent. Most of the other
outcomes involved even smaller departures from the norm…
Direct-to-consumer companies are sometimes accused of peddling
“recreational genetics,” and there’s no denying the horoscopelike
fascination of learning about genes that predict your traits. Who
wouldn’t be flattered to learn that he has two genes associated with
higher I.Q. and one linked to a taste for novelty? …Then there are the genes for
traits that seem plausible enough but make the wrong prediction about
how I live my life, like my genes for tasting the bitterness in
broccoli, beer and brussels sprouts (I consume them all), for
lactose-intolerance (I seem to tolerate ice cream just fine) and for
fast-twitch muscle fibers (I prefer hiking and cycling to basketball
and squash). I also have genes that are nothing to brag about (like
average memory performance and lower efficiency at learning from errors), ones whose
meanings are a bit baffling (like a gene that gives me “typical odds”
for having red hair, which I don’t have), and ones whose predictions
are flat-out wrong (like a high risk of baldness).
Pinker follows up with some interesting observations what he calls “Geno’s Paradox”:
Individual genes are just not very informative. Call it Geno’s
Paradox. We know from classic medical and behavioral genetics that many
physical and psychological traits are substantially heritable. But when
scientists use the latest methods to fish for the responsible genes,
the catch is paltry.
Take height. Though health and nutrition can affect stature, height is highly heritable…
Height should therefore be a target-rich area in the search for genes,
and in 2007 a genomewide scan of nearly 16,000 people turned up a dozen
of them. But these genes collectively accounted for just 2 percent
of the variation in height, and a person who had most of the genes was
barely an inch taller, on average, than a person who had few of them.
If that’s the best we can do for height, which can be assessed with a
tape measure, what can we expect for more elusive traits like
intelligence or personality?
Read the whole thing.