Understanding Psychology (10th Ed)

developmental psychology
The branch of psychology that studies 
the patterns of growth and change 
that occur throughout life.
nature–nurture issue
The issue of the 
degree to which environment and 
heredity infl uence behavior.
 Key Concept 
How do psychologists study 
the degree to which develop-
ment is an interaction of 
hereditary and environmental 
factors?
M O D U L E 3 5 
Nature and Nurture: The Enduring 
Developmental Issue
Gerald Levey and Mark Newman
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382 Chapter 
12 
Development
functioning on development. Such theories stress the role of heredity and maturation —
the unfolding of biologically predetermined patterns of behavior—in producing 
developmental change. Maturation can be seen, for instance, in the development of 
sex characteristics (such as breasts and body hair) that occurs at the start of adoles-
cence. Furthermore, the work of behavioral geneticists, who study the effects of 
heredity on behavior, and the theories of evolutionary psychologists, who identify 
behavior patterns that result from our genetic inheritance, have infl uenced develop-
mental psychologists. Both behavioral geneticists and evolutionary psychologists 
have highlighted the importance of heredity in infl uencing human behavior (Buss, 
2003; Reif & Lesch, 2003; Ilies, Arvey, & Bouchard, 2006). 
Despite their differences over theory, developmental psychologists concur on 
some points. They agree that genetic factors not only provide the potential for specifi c 
behaviors or traits to emerge, but also place limitations on the emergence of such 
behavior or traits. For instance, heredity defi nes people’s general level of intelligence 
and sets an upper limit that—regardless of the quality of the environment—people 
cannot exceed. Heredity also places limits on physical abilities; humans simply can-
not run at a speed of 60 miles an hour or grow as tall as 10 feet, no matter the qual-
ity of their environment (Pinker, 2004; Dodge, 2004). 
Figure 1 lists some of the characteristics most affected by heredity. As you con-
sider these items, it is important to keep in mind that these characteristics are not 
entirely determined by heredity, for environmental factors also play a role. 
Developmental psychologists also agree that in most instances environmental 
factors play a critical role in enabling people to reach the potential capabilities that 
their genetic background makes possible. If Albert Einstein had received no intel-
lectual stimulation as a child and had not been sent to school, it is unlikely that he 
would have reached his genetic potential. Similarly, a great athlete such as baseball 
star Derek Jeter would have been unlikely to display much physical skill if he had 
not been raised in an environment that nurtured his innate talent and gave him the 
opportunity to train and perfect his natural abilities. 
Clearly, the relationship between heredity and environment is far from simple. 
As a consequence, developmental psychologists typically take an interactionist
position on the nature–nurture issue by suggesting that a combination of heredi-
tary and environmental factors infl uences development. Developmental psycholo-
gists face the challenge of identifying the relative strength of each of these 
infl uences on the individual as well as that of identifying the specifi c changes that 
occur over the course of development (McGregor & Capone, 2004; Moffi tt, Caspi, 
& Rutter, 2006).