Re: Fairy Tail 217
^I'm sure he just meant that he "raised them" like a parent would raise a kid. As in, he just searched for people with extraordinary talent, and taught them how to use it to it's fullest. Given all his decades of experience, and history as a guild master, he should be pretty good finding and nourishing talent.
I'm not completely ruling out the possibility of him boosting their power through artificial means, but it seems unlikely.