Invitation to Psychology

Chapter 2 Theories of Personality 61

powerful environmental influences in people’s

lives: their parents and their friends.

Parental influence—and its Limits

LO 2.13

There must be 2 zillion parenting books, but

despite the different and often contradictory kinds

of advice they offer, they reflect one entrenched

belief: Parental child-rearing practices are the

strongest influence, maybe even the sole influ-

ence, on children’s personality development.

For many decades,

few psychologists

thought to question

this assumption, and

many still accept it.

Yet the belief that

personality is pri-

marily determined

by how parents treat their children has begun to

crumble under the weight of three kinds of evi-

dence (Harris, 2006, 2009; Plomin, 2011):

1

The shared environment of the home has rela-

tively little influence on most personality traits. In

behavioral-genetic research, the “shared environ-

ment” includes the family you grew up with and

the experiences and background you shared with

your siblings and parents. If these had as strong

an influence as commonly assumed, then studies

Aspects of Individual

(e.g., temperament,

learned habits,

perceptions, and

beliefs)

Aspects of Situation

(e.g., opportunities,

rewards or

punishments, chance

events)

The two-way process of reciprocal determin-
ism (as opposed to the one-way determinism of
“genes determine everything” or “everything is
learned”) helps solve a mystery pondered by every-
one who has a sibling: What makes children who
grow up in the same family so different, apart from
their genes? The answer seems to be an assortment
of experiences that affect each child differently,
chance events that cannot be predicted, situations
that children find themselves in, and peer groups
that the children belong to (Harris, 2006; Plomin,
2011; Rutter et al., 2001). Behavioral geneticists
refer to these unique experiences that are not
shared with other family members as the nonshared
environment: being in Mrs. Miller’s class in the
fourth grade (which inspired you to become a sci-
entist), winning the lead in the school play (which
pushed you toward an acting career), or being bul-
lied at school (which caused you to see yourself as
weak and powerless). All of these experiences work
reciprocally with your own interpretation of them,
your temperament, and your perceptions (did Mrs.
Miller’s class excite you or bore you?).
Keeping the concept of reciprocal determin-
ism in mind, let us take a look at two of the most

nonshared environ-

ment Unique aspects of

a person’s environment

and experience that are

not shared with family

members.

Is Susan Boyle, a plain woman who stunned the world with her great voice, a shy, modest introvert or a self-confident
performer? Social-cognitive learning theory holds that genetic dispositions, talents, and personality traits, such as
Boyle’s skill as a singer, cause people to choose some situations over others. But situations, such as Boyle’s appear-
ance on Britain’s Got Talent, in turn influence which aspects of their personalities people express.

About the Influence

of Parents

Thinking

CriTiCally