User blog comment:B214/High School DxD Hero Episodes review/@comment-3965848-20180516173756/@comment-3965848-20190108111047

First: They're not all descendants, they've "inherited the spirits" of those heroes, in theory that could mean the Sacred Gears they have might've belonged to those heroes.

Second: It could also mean their names may possibly be just code names based off of those heroes and not their actual birth ones.