Necile sent me a message a while ago when I talked about my sims "rolling" supernatural conditions. I have been using dice to determine whether or not my sims carry on their parents' supernatural "conditions", but she had a FAB idea for turning this concept into a ROS file!
And so, with a lot of much-needed nagging from Necile, I bring you two ROS files, for your enjoyment.
The "heavy" file is the one I'm currently using. It will give your sims a 2-in-6 chance of the following three options: Creature, Carrier, Clean. It is up to you to determine if "Carriers" display any aspect of their supernatural condition.
The "light" file is for those who don't want a game overrun with supernaturals. With this file, it is 1/6 for Creature, 2/6 for Carrier, and 4/6 for Clean.
My recommendation is to use the "light" file for the children of Carriers. It makes more sense to me, but, as always, it is YOUR game, so you get to pick. XD
If you want to really run these how I do, please refer to the following list:
Aliens: I treat aliens as being "creatures" if they display alien genes, and roll for ones that do not have the skins/eyes/ears. I also use the alien pregnancy rules I developed in the story Seahorse and through my Crystal Ridge BACC. The short version of this is that if a male sim is of alien descent OR has given birth to alien babies, they have a chance of getting pregnant by woohoo with another sim. I generally roll odds for this with the same odds as I have set with riskywoohoo (no actual numbers given due to my tendency to change the odds all the time) Aliens created in CAS do NOT have this special condition. (so, if you're reading Lucy's Valley, Taliesin doesn't count as an alien in regards to pregnancy, while Andi will be able to pass on the ability to get pregnant to any male children she might have)
Vampires: No special rules, though I'm planning on making the change at the adult birthday, rather than the teen one, to avoid crispy teenagers.
Werewolves: No special rules.
Plantsims: If a sim is born via the "spawn plantbaby" option, they may be cured as a toddler, in order to give them a proper childhood, though this is not required. They are not given a random roll for their supernatural condition, but rather are always turned back into a creature on their adult birthday.
Witches/Warlocks: I treat these as THREE SEPARATE supernatural conditions. A good witch can only pass on the good magic gene. Ditto evil and neutral (you'll have to use cheats to pass on the neutral magic gene, since sims have to be completely evil or completely good to do the transforming spell). If you end up with a child of a good and an evil magic user, and roll 'creature' for both races, which you choose to pursue is your choice. I'd make up some big drama, but that is just me. ;)
On the children of two DIFFERENT supernaturals: I'd roll for both conditions, but not require myself to enforce both conditions, if the sim rolls "creature" for both. Especially with something like a plantsim and a vampire, goodness.
VERY IMPORTANT NOTE: Rolling these with the ROS will NOT magically cause your sim to inherit the supernatural condition when they hit the appropriate age. You'll have to use your own methods to cause it to happen. I use a combination of normal game ways (a spell for witches, savaging for werewolves, biting for vampires) and hacks (pollen prank makes plantsims, creature transformer painting thing) depending on my mood/the sim in question.