Yu Yu Hakusho1992

[Captain Otake reveals that Spirit Detective Yusuke Urameshi is a direct descendant of the Mazaku]

Koenma:
That is a vile accusation. And to level it in front of his corpse - it's ridiculous! His mother may act like a monster, but his parents are human. I had an ogre do a background check.

Captain Otake:
True, as were his grandparents and great-grandparents, but if you continue back much further...

Koenma:
[gasps] The Atavism of the Mazaku.

Captain Otake:
That's affirmative, sir. It's through that rare phenomena that we think Urameshi inherited his demon blood. And if we're right, which by all signs we are, he's a genetic time-bomb just waiting to trigger.