My new pony will be 3 in May. He currently stands at about 13hh. Dad was 15hh and mum, 14.2hh. I'm very sure he won't make even his dam's height. Why is he so much smaller than his parents?
You need to look beyond his parents - grandsire and granddam or even further back than that. My pony is a hand taller than both his parents and grandparents. He goes back about five generations to get his height!
could be to do with his genes, somewhere in his family may have been bred with smaller horse/pony ect.
could be his diet when he was young,
could be health,
could be a number of things.
some horses dont stop growing till they get to 5-6 sometimes even 7. i had a horse a few years ago that was 15.1 when i bought him at 3 and a half and when he was 5 he was 16.2hh and then didnt grow anymore. i wouldnt panic to much yet he may grow a bit more over the next year or so (could end up 14.2hh) xx