So very true as one who has crossed breeds back and forth for years! Many of our chickens have as many as 15 breeds in their ancestry, I keep a data base! However a chicken calculator of "pure" chickens can help to get an idea and certainly can help with traits like barring or blue. We got some new blood last year so we had a "pure" Marans rooster that we crossed with a blue cross bred hen. Pure is in quotes as his sisters have enough differences to tell apart on sight. The hen is 13/64 Americana, 5/32 Marans, 5/32 ?, 3/32 Game Banty, 5/64 Game, 7/64 Brazilian Game, 5/64 Wyandotte Banty, 1/32 Leghorn, 3/64 Rock, 3/64 Hamburg, solid blue with muffs. Here are pics of some of the offspring and the parents. The red pullet seems to have some blue tail feathers coming in. We have had this before where the red covers up most of the blue. One blue and two black pullets have gold on their hackle (only pictured one of the black hens). One pullet hen has no color showing in the hackle.A breed calicalur is only possible with so called PURE chickens that have been bred, inbred, linebred, so on and so forth for so long that every lurking gene and rouge bit of DNA has been bred out or more likely left laying on the butcher shop floor. Therefore it is quite possible to get some GENERAL idea of what you will end up with when you cross hen X and Rooster Y because that is already somewhat general knowledge, but the number of unknowns for subsequent generations and future out crosses are IMHO infinite. That is unless you have a database with all the genes and DNA it is possible for chickens to carry, then make you chickens spit into a test tube to be sent off for analisis before you introduce hen and rooster.