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 persons. (Note: you do not need to do a Punnett Square for this problem).

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 persons.  (Note:  you do not need to do a Punnett Square for this problem).

anonymous · Answer

Their son has a genotype of rr. Man and wife's genotype is Rr. The son received the genotype that was 25% possible.

anonymous · Answer

These are the possible genotypes RR, Rr, Rr, rr
First 3 carries dominant gene for tongue rolling, so they can do it, while the 4th genotype rr is homologous for recessive, and he/she can't perform tongue rolling.

anonymous · Answer

Rr   Rr                 Both parents can do it beacuse Rr is Tounge Roller but they give only
\    /                    one of the genes to their child, if both give "r" then the kid would not
  rr                      be able to roll his tounge