That's the problem, I tried and he has a mix of all the roos and hens that he purchased through the hatchery (as black sex links to my understanding) and raised all together in the same coop/run.
And this is why I don't get into genetics...lol
This is what I had found when I went looking:
[COLOR=222222]When we breed a barred male to solid color females, his daughters get a normal and full dose of barring and his sons get only one gene, or half the normal dose, of barring. If the hen used was black, all the chicks will be barred. If the hen carries the silver gene, then the daughters will be barred and the sons white or white with barring. As chicks, we would see yellow down on males and black down with white spots on females.[/COLOR]
[COLOR=222222]Black sexlinks are the result of crossing a Rhode Island Red or New Hampshire Red rooster over Barred Plymouth Rock females. Both sexes hatch out black, but the males have a white dot on their heads. Pullets feather out black with some red in neck feathers. Males feather out with the Barred Rock pattern along with a few red feathers. Black Sexlinks are often referred to as Rock Reds.[/COLOR]
http://countrysidenetwork.com/daily/poultry/chickens-101/understanding-sex-link-hybrid-chickens/
I have blacks with white dots, blacks with no dots, yellows and yellow/redish lol
According to my nephew, he plans on bringing down like 30ish Guinea, (I believe he said pearl?) eggs. Apparently now he knows what is what. We'll see.
[COLOR=222222]So to answer the original question, all I know is they are black sex link offspring or black sex links lol[/COLOR]