The Bug

Baby mobs will always stick around their parents, but because a mule can only come about from a horse and donkey breeding, it will not display the same behavior. However, if there is an adult mule nearby it will act as if that was its parent.

Reproduce

• Breed a horse and a donkey to get a mule
• Lead the horse and donkey away
  Notice the baby mule doesn't follow its parents

Expected Result

The baby mule would follow the horse or donkey since those were its parents