“People without children” then that is caused by external factors that causes mutation in genes or diseases, so you can not classify them as not alive sincetheir species (Parents) are able to reproduce. When it comes to mules, their sterility is caused by being a hybrid of donkey and horse (not the same specie). Example, the cells in the human or mule body reproducing constantly.
It is impossible in this case because both partners have homozygous alleles. The child will have Ww and because W has complete dominance the child will have a widows peak
