Share and Share Alike!

We've been (sort of) teaching Nathan to share. I know many experts say that, at this age, children don't quite understand the concept and sharing shouldn't be rigidly enforced. I'm cool with that. I figure, if something is Nathan's and he's playing with it, he can choose to share it or not. The only real problem we've had with sharing is when Evan gets something that used to be Nathan's. Things like the baby swing, jumper, bouncy seat, electronic toys... Nathan will say, "that's Nathan's!" Laura usually says something like, "you need to share it with your brother." I have started saying, "that's Evan's now." Anyway, Laura had some yogurt and fruit a couple of nights ago, and she had a pudding cup for Nathan. Nathan decided he'd rather her snack, and started eating all of her strawberries. When she told him, "Nathan, that's mommy's snack," he looked at her sternly and replied, "Mommy needs to share with Nathan!"