Kinship coefficients! Race exists
 
Genetic predispositions, within an environmental context, or acted upon by environmental pulls/inputs
 
There are criticisms of twin studies, but they revolve around saying the estimations discount environment too much or overestimate heritability. However the jump from non-identical to identical or twins reared apart compared to how adopted siblings are as strangers shows the trajectory of reducing environmental impact. Criticisms dont justify going back to blank slatism