Fraternal twins are genetic through the mother's line, so does that tell us something about Elena's birth family or is it just werewolf magic deciding one pup wasn't enough?

Earlier in the series it was suggested that Elena’s mother might be descended from the Russian Pack. That’s never been confirmed, but the fact she’s one of the few people who survived the bite–and had fraternal twins who…well, that’s a spoiler for Forsaken!–let’s just say it’s partly genetic with a little magic thrown in.