Well they will be combination chickens, uniquely feathers, so they will be easy to tell a part. And they probably will grow up just fine and lay eggs for you.
Pure bred birds are carefully bred and selected to breed based on specific characteristics. They become more uniform in expected outcome. When one just sees what happens, it is rather a crap shoot what you will get. If one did this type of breeding over many generations one would have less dependable egg laying, and smaller carcasses if harvesting for meat. But it would take maybe 10 years of mishmash breeding before one would get obvious problems.
A few years ago, I had rather a ragtag bunch, and bought a very nice rooster... amazing how a pure breed rooster over those girls produce a much better hen.
Also, sometimes you get what is call hybrid vigor, which is a more spritely lively hen, do to the mixing in of new genetics. In cattle a famous crossing of angus and hereford produced a black baldy that did better than either pure bred calf for quite awhile, now however, the pure bred have caught up to them.
So my point is, have fun. Such a fun hobby.
Mrs K
