>>714459123
While genetics do play a part in warp powers the primarchs original souls were basically super concentrated warp stuff the emperor created/stole and stuffed inside the primarchs. And it effects everything about what they are not just psychic powers, but also their strength, intelligence, and charisma. Without their original souls they're basically just super primaris marines.
>>714459931
Raptors seem to be based on the green berets to me. They work in small teams, take command of local forces, and are experts in guerrilla warfare.