Later came the New Mutants with younger characters possessing mutant powers that sometimes did actually possess them (the only type of comic book story I do not like).
They call this Young Adult Fiction - YA in publisher's info. http://Bachelor-Fp.Phys.Uni-Goettingen.de/doku.php?id=the_most_innovative_fiction_autho_s_in_ame_ica_by_numbe_of_sales