Behavior - Research Article from Macmillan Science Library: Genetics

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Twin and Adoption Studies

To determine whether variation in some dimension of behavior is heritable (whether behavioral differences are, in some part, due to genetic differences between people), human researchers use family, twin, and adoption designs. The first step in determining whether a behavior is influenced by genes is to establish that it aggregates or "runs" in families. Similarities in behavioral characteristics among family members suggest that genes influence the trait, but they cannot conclusively demonstrate genetic influence, because family members share their experiences (i.e., their environments) as well as their genes.

Twin and adoption studies allow one to tease apart the effects of genes and environments. Twin studies compare the patterns of behavioral characteristics between identical, or monozygotic (MZ), and fraternal, or dizygotic (DZ), twins. MZ twins share 100 percent of their genetic information, whereas DZ twins share, on average, one-half, just like non-twin siblings. Thus, the presence...

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This section contains 2,389 words
(approx. 8 pages at 300 words per page)
Buy the Behavior Encyclopedia Article
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Macmillan Science Library: Genetics
Behavior from Macmillan Science Library: Genetics. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.
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