Finally had a hybrid sim without trying! And I have no idea how.

My spellcaster and werewolf sim had a vampire/werewolf hybrid. He drinks blood, but can perform werewolf actions and has werewolf reward points too. I don't think he'll ever transform into a werewolf though. I can't figure out how this happened - it can't be from the dark ley line lot trait, but whatever, I'm happy to have a hybrid!

What are your experiences with hybrids??? Any tips on how to create more??