11.3 Temperament and Heredity

11-3 What have psychologists learned about temperament?

As most parents will tell you after having their second child, babies differ even before gulping their first breath. One aspect of personality—temperament (emotional reactivity and excitability) is quickly apparent, and it is genetically influenced (Kandler et al., 2013; Rothbart, 2007). From their first weeks of life, some infants are noticeably difficult—irritable, intense, fidgety, and unpredictable. Others are easy—cheerful and relaxed, feeding and sleeping on predictable schedules. Still others tend to be slow to warm up, resisting or withdrawing from new people and situations (Chess & Thomas, 1987; Thomas & Chess, 1977).


Consider how researchers have studied these issues with LaunchPad’s How Would You Know If Personality Runs in the Genes?

Temperament differences typically persist. Consider:

The genetic effect appears in physiological differences. Anxious, inhibited infants have high and variable heart rates and a reactive nervous system. When facing new or strange situations, they become more physiologically aroused (Kagan & Snidman, 2004; Roque et al., 2012). One form of a gene that regulates the neurotransmitter serotonin predisposes a fearful temperament and, in combination with unsupportive caregiving, an emotionally reactive child (Raby et al., 2012).