Biology Punnet Square Question

[ab94]

Homework Statement

The Xolo is the national dog of Mexico. The striking characteristic of this dog is that it
has no hair. Xolos carry a mutation in Chromosome 17 that, when homozygous, is lethal.

If two hairless Xolos were mated, what fraction of their surviving offspring would be hairless?

Homework Equations

The Attempt at a Solution

If two hairless Xolos were mated, assuming Hh and Hh since homozygous would not exist, then 1/4 would be HH 1/4 would be hh and these would die because they're homozygous. and 2/4 Hh.

Therefore 50% would have no hair. But the answer is 2/3 will have no hair, why?

 

[AGNuke]

I think HH should be lethal and not hh because it is the dominant Chromosome 17 trait, while h is its recessive counterpart (meaning that Xolos must have hair), it should not be lethal when present as hh.

So, HH will die, so 2 Hh will not have hair, while hh will have hair. So, answer's 2/3.