How about randomised the lot traits and let the trait stay until the first couple of the house died & starts randomised again the lot traits for every generation?
It's quite fun & challenging. For example, in my saved game, I have a normal Sims parent given birth to a twin (1 of them is a vampire & the other one is a normal Sims - due to on a dark lei line). I also have a normal Sims parent given birth to a twin of vampires. I also have a house where it is haunted & the residents have to deal with it every single night. It's kinda fun to mix & match the lot traits. :D