Question

Alex had two black rats (dominant). He allowed his black rats to mate and was shocked to see that three of the rat babies were black and one was an albino! What genotypes were the parents?

Answer 1

i think it is co-dominant

Answer 2

In order for the off springs to have a 3:1 ratio, the parents must have been heterozygous. Both blacks rats must have carried the dominant allele and a recessive allele.