Truly ex­cep­tional in­di­vid­u­als, weak or strong, are, by de­f­i­n­i­tion, to be found at the ex­tremes of sta­tis­ti­cal curves…Since each in­di­vid­ual pro­duced by the sex­ual process con­tains an unique set of genes, very ex­cep­tional com­bi­na­tions of genes are un­likely to ap­pear twice even within the same fam­ily. So if ge­nius is to any ex­tent hered­i­tary, it winks on and off through the gene pool in a way that would be dif­fi­cult to mea­sure or pre­dict. Like Sisy­phus rolling his boul­der up to the top of the hill only to have it tum­ble down again, the human gene pool cre­ates hered­i­tary ge­nius in many ways in many places only to have it come apart in the next gen­er­a­tion.

E.O. Wil­son⁠⁠, On Human Na­ture⁠ 1978