I had my colt gelded a year ago and he'd been separated from his mother for some time running up to this. Her milk had dried up.
I put him back in the field with her about a month after he was gelded and there are 2 other geldings in the same field.
Yesterday, I turned mother and son out together in a different pasture with just a goat in there and my gelding has suddenly started trying to nurse from his mother again. He got a hoof in his face for his trouble. Then he looked like he was trying to mount her (she's not in season).
Is this because of the goat or is he just a "Momma's boy" like my husband says and he also thinks the gelding was trying to get his mother to play and was not trying to mount her at all. I didn't notice anything like this going on when he was with the other 2 horses and his mother but I'm thinking my "boss" gelding would not have allowed that behaviour.
Also, he's only acting like this when I'm outside, if I watch him from the window, he just grazes.