Personality theorists have long grappled with the relative roles of nature and nurture in shaping personalities. Some theories, such as trait theory and psychoanalytic theory, stress the role of inherited
biological predispositions, whereas others, including behavioral and humanist theories, stress the role of learning and life experi- ences. Let’s look at the roles that heredity and biological predispo- sitions (nature) and environmental situations (nurture) play in forming personality.
Do We Inherit Personality? Even newborn babies differ in temperament, which implies that it is hereditary. Temperament, the “raw material” from which per- sonalities are formed, refers to the hereditary aspects of your per- sonality, such as biological predispositions to be sensitive, irritable, and distractible and to display a typical mood (Rothbart, 2007). Temperament has a large impact on how infants interact with their parents. Judging from Annette’s adult personality, you might guess that she was an active, happy baby.
Even newborn babies differ in temperament, which implies that it is hereditary. Temperament has a large impact on how infants interact with their parents.
At what age are personality traits firmly established? Personality starts to stabilize at around age 3 and continues to “harden” through age 50 (Caspi, Roberts, & Shiner, 2005). However, as mentioned earlier, personality slowly matures during old age as most people continue to become more conscientious, agreeable, and emotionally stable (Roberts & Mroczek, 2008). It appears that stereotypes of the “grumpy old man” and “cranky old woman” are largely unfounded.
Does the stability of personality traits mean that they are affected by heredity? Some breeds of dogs have reputations for being friendly, aggressive, intelligent, calm, or emotional. Such differ- ences fall in the realm of behavioral genetics, the study of inher- ited behavioral traits. We know that facial features, eye color, body type, and many other physical characteristics are inherited. So are many of our behavioral dispositions (Bouchard, 2004; Kalat, 2009). Genetic studies have shown that intelligence, lan- guage, some mental disorders, temperament, and other complex qualities are influenced by heredity. In view of such findings, it wouldn’t be a surprise to find that genes affect personality as well (Nettle, 2006).
Adult personality is influenced by identification with parents and imitation of their behavior.