At the park the other my son pushed another little boy. The little boy was playing with my sons favorite toy and my son became impatient when the other little boy wouldn't leave it alone...
I know he didn't learn this behavior from me, my husband, or his babysitter...there was only one place he could learn it and that is the nursery at the church... Although, I do not think that my son was being aggressive, I believe this was a failed attempt to initiate play with a peer, it is always good to read up and learn about behaviors before they become problems. We have found a Mommy and Me group to join so we can learn how to meet and play with children our age.
I found this article about children and aggressive behavior and I think it is awesome. I hope it is helpful. It is put together by N.C. State University.