When the boys first discover girls, there is often some testing of the boundaries. I'll see them try their sisters once or twice, sometimes their brothers, but if they get violent about it, exhibit forced mating or if it's an ongoing behavior I'll mark them for culling. Most of them go after the adult hens during this period, and get chased away.
The attraction to young pullets is a complicated issue because I can't see this behavior until they're large enough to mate easily, have adult pullets or hens around, and also have young pullets around that haven't reached sexual maturity.
Under those conditions, if one of the cockerels is going after the young pullets, yes I will cull him.
In the most recent generations I'm not seeing it much. I had one earlier this year that killed a 12 week pullet but I wasn't sure which one it was. The one I suspect is long gone because of other behavior problems.