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Furthermore, it is important to reiterate that although genetics is important, and although we are
learning more every day about its role in many personality variables, genetics does not determine
everything. In fact, the major influence on personality is nonshared environmental influences,
which include all the things that occur to us that make us unique individuals. These differences
include variability in brain structure, nutrition, education, upbringing, and even interactions
among the genes themselves.
The genetic differences that exist at birth may be either amplified or diminished over time
through environmental factors. The brains and bodies of identical twins are not exactly the same,
and they become even more different as they grow up. As a result, even genetically identical
twins have distinct personalities, resulting in large part from environmental effects.
Because these nonshared environmental differences are nonsystematic and largely accidental or
random, it will be difficult to ever determine exactly what will happen to a child as he or she
grows up. Although we do inherit our genes, we do not inherit personality in any fixed sense.
The effect of our genes on our behavior is entirely dependent upon the context of our life as it
unfolds day to day. Based on your genes, no one can say what kind of human being you will turn
out to be or what you will do in life.
KEY TAKEAWAYS
- Genes are the basic biological units that transmit characteristics from one generation to the next.
- Personality is not determined by any single gene, but rather by the actions of many genes working together.
- Behavioral genetics refers to a variety of research techniques that scientists use to learn about the genetic and
environmental influences on human behavior. - Behavioral genetics is based on the results of family studies, twin studies, and adoptive studies.
- Overall, genetics has more influence than do parents on shaping our personality.
- Molecular genetics is the study of which genes are associated with which personality traits.
- The largely unknown environmental influences, known as the nonshared environmental effects, have the largest
impact on personality. Because these differences are nonsystematic and largely accidental or random, we do not
inherit our personality in any fixed sense.