I had a colony of cats that were descended from a grey longhair, and a chocolate point longhair”Siamese.” Over the years, I dealt with dozens of kittens. Grey tuxedos differed somewhat from tuxedos, but a lot of what you say holds for my experience. Siamese were 1 in 4 early on, increasing as the likelihood of them becoming the father of succeeding litters. Blacks, whites(Siamese) greys were all in the mix. (Dominat:color : black, double recessive, white, blended, grey) Mixing things up, there was the tuxedo gene, and a longhair gene, thrown in, so rag dolls were a possibility. Most were probably “ domestic shorthairs” generally, but even littermates seemed to have varying behavioral traits , by color.
I don't suppose you've seen this book about Ernie?