Alan is an adopted child who lives with three siblings, all biological children of his adoptive parents. Alan's math skills are far better than those of his adoptive parents or his adoptive siblings. This provides evidence that: a. shared familial influences play a stronger role than was previously believed. b. genes may have a stronger effect than familial environment on talents. c. few environmental effects on personality come from outside the family. d. Alan's own initiative to excel is greater than that of his adoptive family.