Chapter 3 Puberty and Biological Foundations - The McGraw-Hill ...

The relative contributions of heredity and environment are not additive. That is,
we can’t say that such-and-such a percentage of nature and such-and-such a percentage
of experience make us who we are. Nor is it accurate to say that full genetic expression
happens once, around conception or birth, after which we carry our genetic
legacy into the world to see how far it takes us. Genes produce proteins throughout
the life span, in many different environments. Or they don’t produce these proteins,
depending in part on how harsh or nourishing those environments are.
The emerging view is that many complex behaviors likely have some genetic loading
that gives people a propensity for a particular developmental trajectory (Plomin &
others, 2001). However, the actual development requires more: an environment. And
that environment is complex, just like the mixture of genes we inherit (Coll, Bearer,
& Lerner, 2004; Overton, 2004; Sternberg & Grigorenko, 2001). Environmental influences
range from the things we lump together under “nurture” (such as parenting,
family dynamics, schooling, and neighborhood quality) to biological encounters (such
as viruses, birth complications, and even biological events in cells) (Greenough, 1997,
1999; Greenough & others, 2001).
Imagine for a moment that there is a cluster of genes somehow associated with
youth violence (this example is hypothetical because we don’t know of any such combination).
The adolescent who carries this genetic mixture might experience a world
of loving parents, regular nutritious meals, lots of books, and a series of masterful
teachers. Or the adolescent’s world might include parental neglect, a neighborhood in
which gunshots and crime are everyday occurrences, and inadequate schooling. In
which of these environments are the adolescent’s genes likely to manufacture the biological
underpinnings of criminality?
A controversy erupted when Judith Harris (1998) published The Nurture Assumption.
In this provocative book, she argued that what parents do does not make a difference in
their children’s and adolescents’ behavior. Yell at them. Hug them. Read to them. Ignore
them. Harris says it won’t influence how they turn out. She argues that genes and peers
are far more important than parents in children’s and adolescents’ development.
Genes and peers do matter, but Harris’ descriptions of peer influences do not take
into account the complexity of peer contexts and developmental trajectories (Hartup,
1999). In addition, Harris is wrong in saying that parents don’t matter. For example,
in the early child years parents play an important role in selecting children’s peers and
indirectly influencing children’s development (Baumrind, 1999). A huge parenting literature
with many research studies documents the importance of parents in children’s
and adolescents’ development (Bradley & Corwyn, 2004; Collins & others, 2000,
2001; Collins & Laursen, 2004; Collins & Steinberg, 2006; Maccoby, 2002; Parke,
2004). We will discuss parents’ important roles throughout this book.
3
Review and Reflect ● LEARNING GOAL 3
Explain the contributions of evolution, heredity, and
environment to adolescent development
Review
• What role has evolution played in adolescent development? How do the fields
of evolutionary psychology and evolutionary developmental psychology describe
evolution’s contribution to understanding adolescence?
• What is the genetic process?
• What is the nature of heredity-environment interaction?
Reflect
• Someone tells you that he or she has analyzed his or her genetic background
and environmental experiences and reached the conclusion that environment
definitely has had little influence on his or her intelligence. What would you say
to this person about his or her ability to make this self-diagnosis?
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Evolution, Heredity, and Environment 89
Heredity
Heredity
Heredity–Environment
Correlation View
Epigenetic View
Environment
Environment
FIGURE 3.17 Comparison of the Heredity-
Environment Correlation and Epigenetic Views
The interaction of heredity and environ-
ment is so extensive that to ask which is more
important, nature or nurture, is like asking
which is more important to a rectangle, height
or width.
—WILLIAM GREENOUGH
Contemporary Psychologist, University of Illinois
www.mhhe.com/santrocka11
Genes and Parenting
Heredity Resources