why may a rabbit look totally different from its parents?

I'm not sure if it's possible for a rabbit to be totally different from BOTH parents, but it's really possible for it to be different from one of it's parent. The one chance it could be totally different is from mutation. It's can become different from one parent by the rules of reproduction. If you know about the punnet squares you'll know what i'm talking about. Parents have traits that are dominant or recessive. Those are called dominant/recessive alleles. For example with the rabbits, the brown ear can be dominant and white ear can be recessive. A parent with brown ears can have both dominant alleles, or one dominant and one recessive allele. Only one dominant allele is needed for it to have that trait, so it's highly possible that it that trait. Each parent pass on one allele, and if one of them is dominant, then the baby will definitely get that trait. But if both parents pass on recessive, then the baby will have that trait.

That the most I can explain with out diagrams. HOPE THIS HELPS!!! ;D

because of their genes.