…”[G]enome-wide” surveys examine the links between a trait and all of the 20,000 or so human genes.
This has been an extraordinarily powerful approach. For the most part, what has emerged from these studies is evidence of the minimal extent to which some trait is “in your genes” and of how relatively unimportant any given gene is.
The single genetic variant that was most powerfully associated with growth explained just 0.4% of the variation in growth, and all the hundreds of identified variants put together explained only about 10% of the variation — which is not a lot of explanatory power.
An equally acclaimed study used similar techniques to study body-mass index (BMI). After research on nearly 250,000 subjects, the genetic variant most clearly identified with BMI accounted for only 0.3% of the variation.
The most predictive single genetic variant accounted for 0.02% of the variation between individuals. Putting together all of the identified genetic variants explained only about 2% of the total variation.
Source: The Wall Street Journal.