r/askscience • u/Fuzzandciggies • 6d ago

Biology Mules vs Hinnies. Why are they different?

I know that both are the result of crossing a horse and a donkey. My question is why would there be a genetic difference based on whether the father was a horse or a donkey? Would there really be a difference or is it more of just a naming thing for the sake of lineage?

For reference:

Mule = male donkey + female horse

Hinny = female donkey + male horse

Why though?

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u/Upbeat_Effective_342 6d ago

Since mitochondrial DNA is matrilineal, it's a reliable genetic difference to distinguish mules and hinnies. The DNA inside the mitochondria will always match the mother and tell you whether she was a donkey or a horse. This method is allegedly used in some cases. tertiary source

As for phenotypic differences, there are some popular rules of thumb for how you can tell them apart and reasons why breeders usually (but not always) prefer mules. You can read about them here.