Single comb is recessive to Rose comb. So having a Single comb means that all of their offspring would inherit at least one copy of that gene. I would not breed a Single comb unless the bird was perfect in every other way. What do you want to actually breed them for since you are breeding GLW and SLW together?I got a question ? If Iv'e got a GLW Roo one GLW Hen and 4 SLW Hens, 2 of my SLW Hens have single combs, what would be the chances of them having off springs with single combs? Or should I just leave the 2 SLW Hens out of breeding all together?