Hello, so I’m thinking at this point of 3 months that one is a roo & one is a hen, help me if ya will.
I’m betting it’s a cockerel. Compared to the one behind it, if they are the same age, has much less red on top of its head. The one in the front has a big comb already.
Yes they were bought together and they were the same size when I got them at a couple of days old. Both are 3 months!
If you do in fact have one of each, their lacing will develop in different patterns, with the female's being quite uniform over the whole body.
The fact that they are the same age but there is such a prominent size difference worries me. Even if one is a male and the other is a female there shouldn't be such a large size difference. The smaller one looks like it has coccidiosis, especially by the way it's standing, which can stunt the chicks growth. You may want to look into treating the smaller one if it is not getting any larger. As for their genders: The larger one is a pullet. I can tell by the coloration of her feathers. The smaller one is a cockerel. Note that there is less white in his feathers. Males typically develop slower, but I still don't think he should be that small. Does he always stand like that? Have notice any growth lately?
Front one is a cockerel But they look really under developed for being twelve weeks. Are ou sure about the age?