The socioeconomic status (SES) of the family also plays a role in determining the level of intelligence in the child.  According to the article, observable SES characteristics including parental education, family structure, family income, and parental occupation.  For children whose family income is less than $16,000, heritability accounts for 49% of the variance in intellectual development.   For children in the family income bracket of $16,000 to $60,000, heritability accounts for 83% of the variance.  Low-SES environments decrease the level of heritability of intellectual skills and increase the level of influences from the environment