I have 14 chicks still in the brooder. 10 are about 3 weeks old and 4 are about 6 weeks old. 2 of the youngest group are so much smaller than the other 8. They look to be about a week and half younger then the others. They are all Black Copper Marans from the same hatch. They all seem healthy as well. The 8 all seem to be feathering quite well but the 2 runts aren't feathering nearly as much and are just smaller overall. Do you think they are simply just smaller and no further issue will come of it or should I expect a problem?