My son is 2 and a half and pushes big kids. He's rough and aggressive when he plays with us so he thinks he can do it to anyone.
My daughter just started doing this too, right after being moved to the preschool room and I think she’s getting it from the older kids in her class. She doesn’t listen to me, either. I hear you, it’s so hard!
We are in the same boat! My 2 1/2 year-old started pushing little kids over and has been so mean and I am not sure where she got it from. I think it is just a phase and their age. We try to be with kids more her age, and I’ve had to take her out out of fun situations for not listening.