Identical twins have more similar sleep patterns than do fraternal twins, and North Americans are averaging less sleep than their counterparts of a century ago. These facts best illustrate that sleep patterns are affected by both

Question

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The fact that identical twins have more similar sleep patterns than fraternal twins suggests that genetics play a role in sleep patterns. The fact that North Americans are averaging less sleep than they did a century ago suggests that changes in the environment also affect sleep patterns. Therefore, sleep patterns are affected by both heredity and environment.

Identical Twins Have More Similar Sleep Patterns Than Do Fraternal