I remember hearing somewhere that drafts were introduced to some wild herds on purpose, so it's certainly possible. I'm not sure if you could track down whether or not your horse's herd had this or not, but given her thick neck, I wouldn't bet against it!
I personally think she has some draft in her. I knew a BLM mare that came from a herd and looks EXACTLY like yours, about the same size, except she was a dun. They traced it back & what do ya know, there was a Percheron stud in her old herd. So I believe your baby is part draft. Posted via Mobile Device