It has been said that the heritability of learning ability or of intelligence is irrelevant to teachability. In support of this statement we see it pointed out that a child or a group of children show some response to training, and this is held up as evidence against the heritability of intelligence or learning ability. Most estimates of the heritability of IQ in the European and North American populations on which we have good data fall in the range from 0.60 to 0.90 and most of these estimates are in range from 0.70 to 0.80 (not corrected for test unreliability. The fact that IQ has high heritability surely does not mean that individuals cannot learn much. But knowing that learning ability has heritability does tell us this: if a number of individuals are all given equal opportunity--the same background, the same conditions, and the same amount of time--for learning something, they will still differ from one another in their rates of learning and consequently in the amount they learn per unit of time spent in learning. The fact that scholastic achievement shows lower heritability than IQ means that more of the variance in scholastic achievement is attributable to nongenetic factors than is the case for IQ. Consequently, we hypothesize what the sources of the environmental variance in scholasticachievement are, and , possibly we can manipulate them. (Author/JM)