Horse genetics is fascinating!
Two of my favorites include:
Chimeras (i.e. two embryos fuse in-utero)
and Birdcatcher Spots (genetic cause unknown)
And of course, I've never made hypothetical foals ;)
Because Tesla was an IVF baby, I had to do a paternity test in order to register her.
You pull out a twist of mane, follicles intact for a DNA extraction and sequencing of SNPs, and they send you the results in the mail.
Who's your daddy?