>>12022227>>12022281>>12025433>>12022129>IQ correlates with wealth which correlates with education and better dietVarious studies have found the heritability of IQ to be between 0.7 and 0.8 in adults.
Monozygotic twins, who share 100% of their DNA, have IQs that correlate, on average at .76, meaning their IQs are far more similar than average, even when they were adopted away at birth and raised in totally different homes. MZ twins that grew up in the same home have IQs that correlate at .86, meaning that their IQs are only slightly more similar than they would have been if they never knew each other.
Over the last 100 years, a huge numbers of studies have been conducted which looked at how the degree of IQ similarity between MZ twins, DZ twins, siblings, half siblings, and parent-offspring pairs changes depending on whether or not they grow up in the same home. By comparing the degree of IQ similarity found among these relatives when they live in the same home, and comparing that to how similar it is when they are reared apart, and then comparing this to how similar the IQs are of people who were adopted into the same home but are biologically unrelated, behavioral geneticists can estimate the amount of IQ variation which is due to genes and to the environment. Large reviews of more than 200 such studies have determined that the heritability of IQ lies somewhere between .5 and .7, meaning that 50-70% of IQ variance in the population is explained by genes (Bouchard and McGue, 2003; Hunt 2011 ). By contrast, shared environment, which refers to those aspects of the environment which make people who live in the same home more similar than average, accounts for around 20% of IQ variance. Unshared environment, or environmental factors which do not make members of the same home more similar, accounts for even less.
