What is the probability of the little spuds having their dad lips?

The correct answer is 50%.
Homozygous means a person has the same version of a gene and heterozygous means a person has different version of a gene. A person must have two identical copies of the recessive alleles for it to be expressed, while a single copy of a dominated allele can be expressed.

Since each parent transfers alleles to their offsprings, there is a 50 %probability that little spuds will have their dad lips since Mrs. Pototo is also a carrier of a similar allele. Little Spuds will receive one (r) from his father and has a 50% chance of having any of his mother’s dominant genes.