They do often naturally fall to both sides, but I was always taught that for neatness' and appearance's sake it was best to train them to one side. It does look better, and for some competitions we had to braid their manes always on the right side. So it is just general convention, I suppose.

As far as unicorn horns go, I always assumed they just used superlight materials plus some kind of strong glue (soluble, hopefully). It would have to be something they get used to as most horses would probably try to shake it off the first few times. (I'm also interested in your morphological study, btw, let me know how that goes).

My grey was usually well-behaved, but he was seldom 100% grey either, unless he had just been bathed. He knew how to get dirty, that horse.

OK rambling again...THANK YOU FOR MUTUAL HORSE-SQUEE!!