my headcanon (since I still need to go back and do more DC Atlantis lore research) is that Atlantis had a significant homo magi population and a lot of magic infused technology prior to them being submerged and evolving into the Atlanteans they are today. that would explain why they have such an intimate relationship with magic and sorcery.
so I guess it would more fair to say that the Atlantian magic users are technically homo magi but they are just a variant within the Atlantian species/race; since the homo magi gene won't affect anything other than the ability to use magic.