What chick size for a mix between Phoenix hen and RR rooster?

[Kool-Kemp]

I have a Phoenix hen that mated with a RR roo, and she is sitting on some of her (small) eggs now. My question is will the chicks that she hatches be the size of Phoenix or RR chicken? And what determine the body size of mixed chicks (when they are full-grown)? The mom size or dad size?

 

[HollowOfWisps]

Both genetics determine size as they will inherit 50/50 traits from each side. Usually they will be somewhere in-between, but you could still end up with some chicks the size of a Phoenix and some the size of a RR. Mixed breeds are like those mystery bags you sometimes find at stores in that you never really know 100% what you are getting.