I also had Alexander Goth have 3 kids none had Bella's trait because all of them look exactly like Alexander. Just to make sure body parts do transfer I made a very skinny sim with a very out belly which looks like her spine is curved like banana I had about 3 kids and all of them had the out belly and spine shape like a banana. I also did this with a Sim with a very big derriere and some of his kids had the same by teen so yes body parts do transfer to the children. But I am not certain if the skin color blends or not since it is very subtle to me. It does not blend those traits as for as I can tell since the children's hair color was either Bella's hair color or the father's. The game does not care which gender the child is or what trait is passed on so you might get female traits to your male child or male traits into you female child(Some of Bella's children look extremely distorted). The way I see it it takes random traits from the mother and random traits from the father and puts it in the child. Most of her children have her hair color, eye color, eye shape, jaw shape, lips and skin tone. I don't have a mod that would make it bug out and my wife who also had the game could not find it even though she said she had used it before. I did a test on this with Bella Goth and by the end of it she had 17 children. Hey, I'm going into my CAS to make a character and for some reason in the eye menu, at the top the area where you would normally change the color is missing.
