No you haven't created a monster.

It's true (but astonishing to some I'm sure) that our sweet, wonderful little people can be exactly the opposite.

Just keep doing what you're doing by reinforcing values although it may feel like your bashing your head against a brick wall at times. Every now and then I dig out the books on sharing and being gentle for the bedtime story when DS2 has starts to exhibit undesirable behaviour and we talk about them and relate them to our day. Some sinks in.... eventually...doesn't it?...

There's nothing wrong with rewarding good behaviour either - I choose not to think of it as bribery but as rewarding good behaviour (eg, if you are a good boy while we go shopping you can have a ride on the rocket ship) ! I'm also ok with dragging a kicking and screaming 3yo out of the shopping centre.