I guess they never bothered to scale the children to the horses. I've come across some mods that corrects the scaling of children to do some of the things that mods allow children to do more. I don't remember if riding horses was among them.

Yep, some people learn to ride horses very early. The Mongols, for one. I remember an old Dracula comic where Drac tells some poor mortal fool that he had learned how to ride before learning to walk. I see Aryc and Amaryllis like that, considering their background of minor but very old nobility. They would certainly have their twins riding very early.

The screenies are great. Aeronwen and Neldor seem to be made for each other.