I'm scared of singing even when I'm alone?

I don't sing in front of people. I won't there's noway but that's not my problem. The problem is I'm scared to sing even when I'm alone. Even when my parents aren't home I'm tempted to just sing as I clean my room or whatever I'm doing but I stop myself becuase I'm scared of my own voice. Is that something that most people do or am I the only one who won't even sing in the shower?