Some people will lash out and rebel when they feel like they aren't being heard, or they're holding something back from the past. They swallow anger, sadness, and more, and that can turn into depression or the ultimate expression of bad behavior. Children are experiencing the world for the first time, pushing boundaries, and figuring everything out. The good news is that it is a very exciting time. The bad news is that it can be quite stressful for both the children and the parents.