system
Given the following post, respond as if you're commenting on Reddit:
human
Why are there two individual hybrids between horses and donkeys?

Mules are from a male donkey and a female horse.
Hinnies are from a female donkey and a male horse.

If either are still the offspring between a horse and a donkey, why is there a difference?

(Same question applies to Ligers and Tigons)
gpt
Sperm and eggs aren't created equal. In addition to DNA there are many cellular factors transmitted from ova to offspring. This results in differences in the new hybrids based on what the mother species was.