Pretty much the entire body of genetic IQ studies over the last 30-some years have been consistent on this, so asking for "the studies" on this is like asking f

Pretty much the entire body of genetic IQ studies over the last 30-some years have been consistent on this, so asking for "the studies" on this is like asking for "the books" on calculus. Take your pick! Here is an example: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270739/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270739/ "The heritability of intelligence increases from about 20% in infancy to perhaps 80% in later adulthood."