Queston on Labs

My household we have Three wonderful Labs. WE started with one and then she had a litter. We keep two of the boys. Now one of the boys is starting to show signs of some aggression. We treat our dogs with all the love and right training. I am not sure what to do. We really are confused on what to do. Please any advice???

Might be worth going into more details. Ages of the dogs, more details on what behaviour he's showing & when it happens, when it started, what you've tried so far, etc.
Might be worth contacting a behaviourist locally to you too though - this is a mainly UK based forum and although there's some very dog-savvy members on here, none of us will have seen the dogs in action and a behaviourist can see the whole picture, instead of what you see/what you think you see.

You do not say how old yourpups are but I note that you have kept two male siblings, not something that most people recommend.

Are they both entire?
Is the bitch still entire?
How old are the pups.
Please elaborate on what you mean by aggression.

To dogs, to humans, to each other only?