Question

The ability to roll the tongue (R) is determined by a dominant gene while the recessive gene results in the inability to roll the tongue (r). A man and his wife can both roll their tongues and are surprised to find that their son cannot. Explain this by showing the genotypes of all three pesons.

I think both the mother and the father's genotypes are Rr (heterozygous).
And the child probably has a homozygous recessive trait (rr).

Am I right?
Please check!
Thanks!

Answer 1

yes. both parents are Rr. That is how the child can be rr.

Answer 2

In humans, the gene for right handeness is dominant to the for left hendeeness. A man and a woman both heterozygous for this trait marry. What percent of their children they expected to be right handed? What percent left handed? What are the genotypic and phenotypc ratios?

Answer 3

Wow- this was posted in 2009