Your questions answered
Dr Richard Woolfson's Answer:
Sharing is one of those challenging skills that have to be learned - few children share naturally, without complaint, especially when it's with a younger brother who gives nothing back in return. Your daughter is probably fed up seeing her carefully sorted toys break or disappear in front of her eyes, as her baby brother grabs everything in sight! No wonder she gets annoyed.
There are two ways to approach this. First, explain to your three-year-old that it is kind to share, and that she will benefit when her brothers shares his toys with her (there must be something of his she wants to play with, for instance, his construction toys). It may help to supervise sharing episodes so that, for example, the baby gets one of her toys (for example, a soft toy) for five minutes and then she gets to play with one of his for the same amount of time. Second, continually remind each of your children about the concept of asking before taking. They should never just grab one of the other's toys, without seeking permission. In time, your involvement like this will help both your children learn to share with each other and with their friends.