You used to be able to make a human-mummy hybrid in older patches (I think it's been patched out, but I haven't checked to confirm). It involves having the human father sleep in the cursed sarcophogus for *almost* enough time to become a mummy. Then have the mother get pregnant. I used to finishing turning the father into a mummy in that in between time after the chimes but before the pregnancy moodlet pops up.
The children were strange indeed. As toddlers and children their animations would appear stretched during some movements since the game registered them as mummies (usually adults) and pulled their limbs accordingly. As adults they'd walk around with the mummy shuffle but otherwise appeared normal. They'd also retain water like a mummy, dripping for sim-hours after a shower. I can't remember if their energy bar stayed up or not; I think the mummy kids my test family had wound up with the human needs bars.
I also managed to get simbot/human hybrids, but I can't remember if it was through the game's story progression or with the aid of a mod's story progression. It involved populating a town with nothing but simbot/human couples and waiting for story mode to produce a child for the non-active households. The kids wound up with the simbot animations, some had the simbot needs bars, and they'd short out in water (I wound up giving them hydrophobic traits or they'd pop into the shower or swim in the pool). I'll have to pull up one of those old families and see if the hybridization is still working!
Edit: I found an old screenshot with the mummy kids in walk mode. Creepy little cuties, aren't they?
