This is impossible given our current knowledge of genetics. And frankly, I am not sure we’ll ever be able to figure any of this out with a simple genetic test. Most of these traits are more than just the DNA we inherit.
Let’s take IQ as an example. Most of the studies I have seen point to about half of someone’s IQ coming from genes and the other half from the environment. Any test done right now won’t look at how the environment affected a child’s DNA. And they certainly won’t look at how the environment influenced the growth and development of the brain or how it affected synapse connections or about a million other things to do with intelligence and the brain.
Still, 50% from genes is a lot. If we could get a complete readout of how our genes influence our IQ that might be at the very least interesting. But we can’t.
Scientists believe there are at least 100 genes that contribute to IQ. So far they’ve only identified a handful and none of them have been shown to have reproducibly significant effects on IQ.
For example, scientists have found that having certain versions of the CHRM2 gene affects your ability to organize things in a logical way. The effects aren’t huge though. 23andMe (a company that I have tested with) reports that the variations that they look at in this gene can lead to a 6 point swing in IQ. Woopty doo.
If you drill down a bit farther, some scientists claim that you can get much larger differences. For example, at the furthest extremes, people with one set of variations in this gene averaged an IQ of 85 while people with a second set averaged an IQ of 103. Sounds impressive.
Except that a larger follow up study was not able to see the same effect. In this study, scientists weren’t able to find any connection between variations in the CHRM2 gene and IQ. And CHRM2 is by far the best characterized IQ gene.
Most likely the way that genetics contributes to IQ is that each of the 100 or so genes tweaks IQ a bit higher or lower. So to get a complete readout on IQ you’d need to look at all of these genes. This is difficult to do right now since we only know about a few of them.
And to make things even more complicated, the genetic contribution to IQ probably isn’t a simple summing up of these different variations. They don’t exist in a vacuum—these gene variations all interact with each other too.
What this means is that we may never be able to get an accurate prediction about genetic IQ from our genes. There are lots of possible combinations all with different outcomes. In other words, everyone’s IQ genetics may be unique which would make predictions impossible.
The bottom line is that there is not nearly enough data out there to figure out someone’s IQ or intellectual potential. And this goes for athletic ability, creativity and any other similarly complicated trait. We can’t even predict eye color yet very well from our DNA!
So consumers be aware of what a genetic test can and can’t deliver based on what scientists know. Testing for cystic fibrosis, pretty good. Testing for intelligence, not so much.
A final example. Imagine that Einstein’s parents had tested his genes for IQ with a company that looked at four or five IQ genes. And let’s say that he happened to have versions of these genes that lead to a lower IQ. Of course, since it is Einstein his other 95 or 96 or so IQ genes swamp out the effects of these few genes. But the testing company misses this and recommends that he not take an academic career. A little knowledge is a dangerous thing.
*This is common with genetic studies. There is a promising result with a small group that disappears when scientists look at a larger group.
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Current DNA tests could not have predicted that George W. Bush would be our 43rd President of the United States.