Weird...
Cuz if you cross a cochin, with a silkie you get - some frizzled birds, some smooth and some silkied, those birds are f1 sizzles. Then you use the Sizzled (frizzled) and the smooth, and you get more Sizzles, more smooths and more silkies and some curlie silkies sometimes.
Move up and down the ladder... pushing for silkie type shape, and facial and foot features, and a good topknot.
You breed two Sizzles (frizzles) you get some with two doses - not good, and the rest Sizzled.
If I add silkie back in... I get the scattered assortment of Sizzled, smooth, silkie and frilkie - curly silkie.
Because my pet f4 has a face/comb fault - he's single combed and red faced, I'll be breeding him back to black or blue silkies. Here he is this week...
Some of his progeny will be Sizzles or smooths or silkies hopefully with his coloring.
And I then I keep moving toward the Sizzle standard with the group.
Something in silkie to cochin makes frizzle. I'm no geneticist - I just watch it work.