Many teachers like to be a mystery. They don't want their students to know anything about them, and they don't want to know about their students, either. They are there for one reason--to suffer through the day and get their students to pass whatever year end test they may have so they can get the boss off their backs. This is obviously not a great way to influence children.
Don't be afraid to let your students see some of your personality. Be yourself. Relax a little every now and then. It won't kill your classroom management. Just don't share too much with them.
It is okay for students to know a little about your life and your personality, but they don't need to be in on everything going on with you. Some teachers talk to their students like they are a girlfriend or buddy, sharing personal details about their lives. This is going a little too far.
Don't use your time in class as a time to vent or talk about your feelings too much. That should not be the role that your students play in your life.
You are still an authority figure. Don't lose sight of your role and purpose.