Why does a mule look different from a hinny?
It’s to do with the way certain genes are passed on from each parent. You have only to look at the dramatic difference between ligers (lion father and tiger mother) and tigons (tiger father and lion mother) to see this in action. Ligers grow to enormous size, larger than either of their parents, because the male lion passes on a growth gene that would normally be inhibited by a gene from the lioness. The female tiger does not pass on this gene, so the liger becomes huge. This does not happen with tigons, because the male tiger does not pass on the growth gene the way the male lion does, meaning tigons are no larger than their parents.