The genetics term heterozygous refers to a pair of genes where one is dominant and one is recessive — they're different.
Like all words with the prefix hetero, this has to do with things that are different — specifically genes. This term sounds fancy and confusing, but it’s fairly simple: it has to do with traits you inherited from your parents that are different. Let's say your dad’s eyes are brown, your mom’s eyes are blue, and those heterozygous chromosomes led to your having green eyes. If you inherited the same gene from both parents, it’s homozygous — the same.
