Hi,
From what I've read inbreeding happens when you repeatedly breed brother to sister over time. I guess it is possible that your barred rocks cockeral is related to your barred rock pullets but I don't think there is a way to know that for sure. It's preferable to breed father to daughter. If you were to hatch the eggs you will get from these chickens then you could put those new pullets with your rooster (his daughters). Adding a new rooster would be something you would want to do down the road I think. I hope that helps, I'm far from an expert so if anyone knows more about this I'd love to hear it too. Jen