I have a nephew, 3 yrs. of age. When my sister scolds at him, he too gets angry and throw tantrums. For example, there are times he keeps on opening the refrigerator, my sister keeps on telling him to close it, he's not listening. My sister closed the refrigerator then my nephew too got angry, made a very disturbing noise and threw tantrums. What can we do to discipline a kid like this?