Can someone be a witch and not know it?

Can someone be a witch their whole life and not know it? And if they are a witch, why wouldn't someone try to get this person to join a coven? Could it be that the person is to untrustworthy to be in a coven? I'm sure there has to be some test of character before one is even considered to be in a coven. I'm just uming this. I would like to hear from an honest witch/warlock who would know. Thanks so much.