Yeah... You should get an older horse for younger kids... I got an Appaloosa/Quarter Horse, and she costs a lot of money... She is now 4 years old, but we didn't train her, so she isn't good for children under the age of 11... it would be younger, but she has been around people, so she is decent. I would definetly reccommend an older horse. Maybe one that is even trained... I know that was a hassle for us. If you get a horse that is trained, it will be easier to bond with. Is this your first horse? I learned my lesson to get an older horse for you first horse, but after you have had that horse for a while, and know a little more about what you have to do, then you could get a younger horse, and raise it.
Harley is a mixed breed, but still beautiful.

Hope this helps!