The ability to roll your tongue into a u-shape is dominant to inability. what is/are the genotype(s) of a person that can roll their tongue into a u-shape?

The genotypes of a person that can roll their tongue into a U-shape are  "AA" or "Aa"

Explanation:

Let the trait of being "able to roll up the tongue into a U-shape" be represented by "A"

And the trait of being "not able to roll up the tongue into a U-shape" be represented by "a"

It is given that "A" is dominant over "a"

Hence, a person who is able to roll up the tongue into a U-shape can have either of the two type of genotype

a) Homozygous dominant genotype - AA

b) Heterozygous dominant genotype - Aa

Hence, the genotypes of a person that can roll their tongue into a U-shape are  "AA" or "Aa"

that is wrong, its not thymus.