I have never heard of it being hereditary. But if you have a mare or stallion or both with super sensitive skin then maybe. I would have to think that it is the enviroment that the horse is in more than it being hereditary. We see about a 100 horses or so a year that have sweat itch, fly bite dermititis, summer itch, what ever you want to call it. And there are some good treatments out there. Wether you want to use drugs or no drugs.