IQ vs SES vs Genes

[aphar]

Genetic and Environmental Influences on Cognition Across Development and Context (DOI: 10.1177/0963721413485087).

The current consensus is that
Genes account for between approximately 50% and 70% of the variation in cognition at the population level.

Moreover, the genes explain more variance for older people (20% for newborns, 70% for 18yo).

However, the explanatory power of genes depends on the SES:
For children in low-SES contexts, the heritability of cognition approaches zero, whereas for children in advantaged contexts, genes account for as much as 80% of individual differences in cognition.
IOW,
...genetic influences on cognition are maximized by environmental opportunity...
Also,
... a poverty intervention changed parenting behaviors indirectly through effects on child behaviors; there was no immediate, direct effect of the intervention on parenting behaviors. In other words, the intervention was unable to directly influence parents to provide higher quality care but was able to change child behaviors to evoke more effective care from their parents...

So, it's not all gloom and doom.
Providing a better environment for low-SES kids may increase their cognitive attainment significantly.