Multiple choice

Which of the following variable traits are influenced by a combination of genes and environmental factors?

  1. Freckles

  2. Handedness

  3. Dimples

  4. Tongue rolling

  5. Earlobe attachment
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Some people can curl up the sides of their tongue to form a tube shape. Tongue rolling is controlled by a single gene. However, people can learn to roll their tongue as they get older, suggesting that environmental factors also influence the trait.

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