It can be any family member. What matters is, how would you react if they were dating an Alien, let us say that we have recently made contact and its about a generation later, we are still trying to familiarize ourselves with all of the new races we meet, etc.
I would say (jokingly of course)
Honey, Salarians live till they're 40, dont take the easy way out of dating .
(I mean space aliens)