Have you ever been told that you act like one of your parents? Perhaps a rel-
ative has said, “You’re your mother ’s son (daughter), all right. ”My brother ’s
quick temper has often been described as “inherited from his father.” I know
one couple who were more interested in learning about the family of their
daughter ’s fiancé than about the fiancé. They told me that meeting the new
in-laws would help them see what their future grandchildren would be like.
As these examples suggest, the notion that children inherit characteristics
from their parents is widely held in this society. Not only do people acceptthat parents pass physical characteristics, such as eye color or height, through
their genes, but we often expect children ’s personalities to resemble their
parents ’.
Although conventional wisdom has for years acknowledged the role of
biology in the development of personality, the same cannot be said of many
psychologists. Several decades ago, many academic psychologists looked atall healthy newborns as blank slates, perhaps limited by differences in intelli-
gence or physical skills but otherwise equally likely to develop into any kind
of adult personality. Different adult personalities were attributed to differ-ences in experiences, particularly in the way parents raised their children dur-
ing the child ’s early years. However, this view has changed. No reputable
psychologist would argue that people are born with their adult personalities
intact, but today few psychologists would deny that personality is at least
partly the result of inherited biological differences.
This acceptance of a genetic influence on personality has coincided with a
growing recognition that personality cannot be separated from other biologi-cal factors. Research tells us that not all people have identical physiological
functioning. We can identify differences between people in terms of brain-
wave activity, hormone levels, heart-rate responsiveness, and other physiolog-
ical features. More important for personality psychologists, researchers find
these biological differences often translate into differences in behavior. We ’ll
review an example of this later in this chapter when we look at individual dif-
ferences in brainwave patterns.
We also have seen in recent years a growing recognition that human per-
sonality, like other human features, is the product of many generations ofevolutionary development. Just as biologists find it useful to ask about the
evolutionary function of the physical characteristics of a species, some psy-chologists have found this same question useful in understanding certain fea-
tures of personality.
This growing acceptance of a biological influence on personality is partly
a reflection of behaviorism ’s declining influence on the thinking of academic
psychologists. As described in Chapter 13, early behaviorists tended to ignore
individual differences among newborns, and a few even claimed that with en-ough control over the child ’s experiences they could shape a child into what-
ever personality they wanted. Probably no behaviorist would argue such anextreme position today. The movement away from the “blank slate ”position
has also been stimulated by research demonstrating rather clearly that at least
some of our personality is inherited from our parents. This research is re-
viewed in Chapter 10.222 CHAPTER 9 The Biological Approach