The Ability to Roll the Edges of the Tongue Upward

question 12

Multiple Choice

The ability to roll the edges of the tongue upward in a U-shape has been considered to be an inherited ability. The standard assumption is that tongue-rolling is a dominant allele at a single gene locus. Which of the following would cast doubt on this assumption?

• A) A teacher reports that after testing her class on the ability to roll their tongue, with very little effort the non-tongue-rollers can learn to also roll their tongues.
• B) A student who can roll his tongue has a mother and father, both of whom cannot.
• C) A student who cannot roll his tongue has a mother and father, both of whom can.
• D) Two of the above are situations that would cast doubt on this assumption.

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