Quote:
I found this on another thread a while back. From The Chicken Lady. She also has a page on combs.
https://www.backyardchickens.com/web/viewblog.php?id=9280-
Okay, here's the genetics stuff.
A bird with a walnut comb (your parent birds) can have one of the following four genetic combinations:
(P, P) (R, R) (P, P) (R, r)
(P, p) (R, R) (P, p) (R, r)
In order to have a single comb, a chicken has to have the combination (p, p) (r, r) (all recessive genes).
Therefore, if your chicken really does have a real single comb, your parent birds can't be anything other than (P, p) (R, r).
By the way, the ps and rs stand for pea comb and rose comb. Most comb types come from some type of combination of pea and rose comb genes. It's sort of odd, because it almost seems like more chickens have single combs than any other kind of comb. It just must be that single combed birds are more popular (for various reasons that might not even have to do with comb type) or that single comb x single comb breeds true to comb type every time.