Humans carry two copies of most genes. Individuals that carry two identical variants of a gene are called homozygous whereas those that carry two different variants are called heterozygous. For example, if there are two possible variants labelled A and a, then AA and aa individuals are homozygous, whereas Aa and aA individuals are heterozygous. Suppose two heterozygous parents have a child, and each gives one of its genes to the offspring. (a) How many types of offspring are possible if all that matters is the identity of the genes? (b) In some cases the same variant behaves differently if it is inherited from the mother versus the father. How many types of offspring are possible if we account for such effects?