Mrs_giggles

Not putting your son down or anything but when you say talent what we talking?
I have ridden horses since the age of 4 and as gg says a lot of it depends upon the horse as well as the rider. Horse riding is a very conpetitive and expensive hobby to persue and places at good yards are hard to come by, although location in the country can affect your choices or lack of.
Can't advise you re effect on marriage but my mum took me everywhere whilst i was competing and was happy to do it but then again it was her hobby too, and if your son has to be at competitions training multiple times a week are you willing to do it.
This can include getting up on ungodly sides of 6 am on weekends.
Also your son is 11 bear in no.d that he will be starting high school and the discovery of girls.all that said if he really wants it and is really talented then that's great a good on him.