Excuse the bad pun.
As for genetic evidence…unfortunately it appears our knowledge is fairly limited.
A study on voles found that even though their chromosome numbers range from 17 to 64 between species and the X chromosomes in some species carry 20% of the genome and that females sometimes carry significant parts of the male Y chromosome…despite these variations in genotypes, all voles come out looking basically the same phenotype. Some species look so identical it takes a DNA analysis to tell the difference (other methods of determining species via physical examination cannot tell them apart). What it really comes down to is that we do not comprehend the mechanisms that control the expression of the genes. So this must be taken into account when interpreting the the evidence.