Biology Genetics?

Question

A woman cannot curl her tongue, but both her parents can. Is tongue curling dominant or recessive? what are the genotypes of all persons involved?

Answer 1

A DOMINANT trait 'takes over' for the others. Therefore if you have two copies of the gene, the DOMINANT one will express itself.
T = Tongue curling, t = non-tongue curling.
If T is dominant, someone with TT or Tt will be able to curl their tongue. tt will not.

Her parents are both 'heterozygous' for tongue curling - Tt x Tt. Their possibility for children is TT, Tt, Tt, or tt. The woman is in the unlucky 25% of tt.

If tongue curling is recessive, you need two copies of the gene for it to be expressed. Say C and c, where C is tongue Curling and c is not curling. You'd have a cc, but both her parents would have to both have two copies of CC instead - she couldn't inherit a 'c' copy because neither could have it.

Answer 2

it is a dominant trait.
the genotypes are as follows;
mother- Aa
father-Aa
child-aa