I too wouldn't mind knowing how the rat genetics work. But I don't care to look into it. I have a siamese rat which is normal looking, but when she has litters some are normal siamese, some are dumbo, and some are dumbo rex. Unfortunatly she has only bred for me twice and both times I gave away all the rats thinking there'd be more on the way. I think she might be too old or something. I'll have to look into getting a couple more with some different genes. I like having something differen't to look at sometimes.