Misconception : ”Heritability is informative about the nature of between-group differences"
This misconception comes in two forms, and in both cases height and IQ in human populations are good examples. The first misconception is that when the heritability is high, groups that differ greatly in the mean of the trait in question must do so because of genetic differences. The second misconception is that the observation of a shift in the mean of a character over time (when we can discount changes in gene frequencies) for a trait with high heritability is a paradox. For IQ, a large increase in the mean has been observed in numerous populations, and this phenomenon is called the Flynn effect, after its discoverer. The problem with this suggested paradox is that heritability should not be used to make predictions about mean changes in the population over time or about differences between groups, because in each individual calculation the heritability is defined for a particular population and says nothing about environments in other populations. White males born in the United States were the tallest in the world in the mid-19th century and about 9 cm taller than Dutch males. At the end of the 20th century, although the height of males in the United States had increased, many European countries had overtaken them and Dutch males are now approximately 5 cm taller than white US males, a trend that is likely to be environmental rather than genetic in origin.
