Thoughts on mule genetics

[toonbat 28]

Since mules are canon in the show, we can assume donkeys and ponies can reproduce.  Now, if the pony parent of the couple is a unicorn or a pegasus, would you say it's possible for their foal to be born with wings or a horn?  Could we ever hope to see hinny-corns or peg-asses on the show?

 

Also, since the mules we've seen do not have a cutie mark, do you suppose this means that cutie mark genes are recessive, or are cutie marks simply not genetic at all, but purely magical?

 

And finally, since mules, donkeys and saddle arabians have no cutie mark, could that mean that only ponies get them, and that therefore Zecora's cutie mark is not a cutie mark at all, but just a tatto of some sort?