While psychic abilities are sometimes found among the men of Uruk and Arden, this is extremely rare. Even rarer is the person who actually develops his abilities, for this takes time, and time is better spent on weapons training.
Among the gnomes, things are very different. Gnomes watch their children for proclivities and talents, and provide opportunities for them to apprentice to masters... and they treat psychic talents just as they would any other gift, be it artistic talent, a green thumb, or a knack for gadgetry.
Gnomish children with psychic talents are apprenticed to master psychics, and live with them and their families until their talents reach full bloom. When their apprenticeships are over, and paid for, they return to their birth families and use their gifts in the service of their own family and clan.