I am quite confident saying that no, my children are not bullies. Mr. J is a wonderful child, kind and easy going. He is quite sensitive, and doesn't like to see people upset. While we certainly have issues in terms of listening and behaviour, that is all saved for mom and dad.
Mr.K, well - he is Mr. K. Also a wonderful child. He is quite the dramatic little boy, but when someone is sad/hurt/upset he doesn't like it (except for his brother of course). While he can get physical, I am fairly sure that is an age/stage/lack of communication reaction and should get better in the near future.
Growing up, I would say that I was not a bully. I wasn't always the KINDEST person, and definitely said some not nice things and hurt feelings of others (I clearly remember telling my "best friend" at the time we couldn't be "best friends" anymore, because I had another best friend - and you could only have ONE - that was in 6th grade)
As I got older, a friend of mine (we had grown up together, but I didn't really know her until 7th grade) was bullied. I think the biggest reason, because she stood up to those that bullied another girl in our school, and they ended up taking it out on her. It continued for years, and I don't think I was that good of a friend because I don't remember DOING anything about it. I never stood up for her, because I didn't want to be on the receiving end - she was such a better friend than I.
When I came across this post it reminded me of all this. Please intervene - even if your kids think you are overbearing; be a part of your childs life. Know their friends, know the FAMILIES of their friends - and always be open for them to talk to.