Boxer dogs are pretty gentle dogs when they are around people that love them.
However some Boxer dogs are naturally aggressive especially if you do not give them enough love or train the dog properly to keep them from turning aggressive and getting out of control.
The Boxer Dog breed is also usually more aggressive towards other dogs of the same sex instead of being too aggressive around humans.
But just like any dog breed if you don't train and treat them properly on how to treat people then they can get aggressive and that goes for all dog breeds and not just Boxers.
The Boxer dog breed is also a very strong minded working dog.