When do you think you can see someone's biological influences? As an infant? As a toddler? As an adult?

          I believe that an individual’s biological influences manifest during infancy and progress during development. Often during infancy in regard to the interactions of infants with parents, infants often display biological influences of one parent or the other or sometimes a combination of both. Such interactions even with caregivers other than biological parents and with biological parents help personality develop along with biological influences. Therefore, I believe personality development is a combination of biological influences and the environment. Friedman and Schustack (2011), “the existence of many environmentally based biological influences on personality is another reason to be cautious about assuming hereditary causes of personality” (p. 171). As a father of three children I often saw during infancy how my oldest son and daughter displayed behavior similar to that of myself, while my youngest son often displayed behavior similar to that of my ex-wife.

Reference

Friedman, H. S., & Schustack, M. W., (2011). Personality. Classic Theories and Modern Research (5th ed.). Allyn & Bacon.