I'm in a reddit convo about this now, so I was thinking of Vabbilhea and came back here. Maybe sharing this thread will answer questions. A pure alien doesn't seem to get a bloodline trait. I wish they could.
Yes, that was me. Morgyn has human twins. In StrangerVille. I didn't really get much further with that save. I've tested alien abduction further of George Cahill who I gave the ancient bloodline trait to. He was in the GTW science career getting regularly abducted. He was not once, not ever, a spellcaster at any point in his life, he only had that bloodline trait. Yet even that trait produces some conflict with Senior Pollination Technician #3, and the baby is not alien.
Maybe that's an oversight. And it's so niche, and so unimportant that the devs will never think of it or change it. But for someone playing a long dynasty type save, and every sim has long since inherited a magical bloodline, they simply cannot have an alien baby by abduction. Even if a sim gives up being a spellcaster, well... they can't give up their bloodline trait, so they're locked out from it. To me it makes no sense that such a baby isn't alien.
Emilio does have a strong bloodline though. His blue sister is a 50% alien, she has a strong bloodline too. But the pure aliens, like Vabbilhea and the green sister in this family, never get a magical bloodline. You
can get a magical bloodline on a half alien, but not by abduction. The parent has to be a regular alien.
As you see, I've tried hard to get a bloodline on an alien and so far failed.
WHY CAN'T IT JUST WORK LIKE SULANI MANA! lols Oh well.