I would think that unless you are getting the chicks from a feedstore who really is very uninformed about not only their chicks, but also their source of chicks - sex-linked is sex-linked. For instance down color is genetically linked - so for example, a chick that is black is female and the male would be yellow. This is a very obvious way to establish sex at hatching and is often used with multiple crosses of chickens. So you can have two chickens from the same hatch and they can look very different from each other because they are well, mutts. Very common in production birds - again, genetically engineered so that sexing is obvious.
Sorry, maybe I am not getting what behaviour you are most worried about. To me, all of them still look like they are pullets and aggressiveness and comb/wattle size can vary by mix. Are you absolutely sure they are cockerels at this point? This "sexing" question seems to be an area of the biggest concern. I know it was for me when I was worried one of mine was not a pullet. I can't have roo's so, I was really scared I was going to have to get rid of her and had become pretty attached so I didn't like that idea much. In the end, she's just a hen with very large comb and wattles.