32 Part 1 Foundations of Human Development
Checkpoint
1. Which theory is the most correct?
2. What can often develop from the confl ict between two theories?
3. Give an example of a debate that has been occurring among scientists in
recent years.
What Causes People to Develop Specific Traits?
This question has been asked repeatedly. Is it nature or nurture? Are a per-
son’s personality traits, abilities, skills, and tastes a result of heredity or a result of
environment? Most researchers today will answer both. The question is not a mat-
ter of “which,” but “how much?” How much does heredity affect people’s traits?
How much does their environment or home life affect them? The challenge for
researchers to answer the question of “how much?” is that heredity and the envi-
ronment interact in complex ways.
How Does Biology Infl uence Development?
Do you have blue eyes, freckles, brown hair, the ability to sing, or athleti-
cism? Certain traits such as these are passed to you from your parents through
a complex process at the time of conception, 2-9. At that moment, specific
instructions about you including hair and eye color, among thousands of other
traits, are in your genes. Genes are the part of your DNA (deoxyribonucleic
acid) molecule and are found in every one of your body cells.
The instructions found in
your DNA do not change over
your lifetime. These instructions,
which make you who you are,
remain constant. Your DNA does
not change. If your DNA carries
the instructions for brown eyes,
this eye color will remain the
same throughout your life. Genes
control many things about you
including your physical traits,
brain development, and your per-
sonality and temperament.
No single gene determines
a particular behavior as human
behavior is extremely complex. In
recent years, however, genetics
(the study of genes) have started
to show patterns about how just
one gene can be associated with
different inherited disorders. The
most common example given is
Monkey Business Images/Shutterstock.com
2-9
There are certain traits you have in common with family
members related to you biologically.