I would like to put him with my other horse, but my mom won't allow it. She is afraid the other horse will hurt him. The horse that bites just gets worse as he gets older. He especially bites men and will bite any chance he gets. If you just dab at the horse to tell him to quit, it will just invite him to play more.
Horses bite each other in play.
It is best to discourage this when the foal is very young and never let it form into a habit. BUT young horses are easier to train NOT to bite than older horses. Stallions tend to bite more often than geldings. Also, please let me know your level of experience training horses. If you are not a very experienced trainer, this might be a problem that you will need a professional to help you with.