Also, one is growing feathers more quickly than the other two. I didn't think there was a chance of any of these being a cockerel (they were supposed to be sex links), but do you think any of them look especially mannish?
Red Stars are a type of Red Sex Link. I'm 99% sure your chicks are not Red Sex Links as they would be reddish with some degree of white showing. The chipmunk pattern they have is not typical of Red Sex Links. There are a lot of breeds that have chipmunk pattern chicks. Maybe individual pics of each chick might help?
With that color and yellow legs, your top contenders for breeds should be Welsummers and brown Leghorns. Agree they're not red stars. Post pics again around 6-7 weeks and maybe we can get a better idea then.