Oh, I have a fun one for this...
So, I mentioned these guys on another thread awhile back...this is the Palmer family.
The mom (Jessie) is actually a half-alien hybrid. She is married to a human Sim as well. And yet two of her three kids (the two standing up) are full-blooded aliens. Yes, even Harbor-the little boy in the red. He has an alien voice, he can disguise himself, and when in CAS he has the "known alien" trait-even though he has human skin. (Not to mention every time he ages up he gets the default alien outfit, just like his sister. All 3 are kids in my game now.)
Here are all 3 as children with their (very human) dad...
(For reference, Harbor and the other boy (Moat) are twins, while the girl (Ocean) was a second, single birth.)