Depends. If you have a close friend that has known you since childhood, then it's false, because your friend knows you better than you do.
The only way you'll get to know yourself better is if you write a journal or a diary, pouring out your thoughts, actions, feelings, and you read it in a third person view. That will give you an idea on who you are.
I can tell most of you probably will not understand what I am talking about, but if you tried it, you will. Or try asking the honest opinions of others about you, you'll be surprised by the answers they'll give you. Which will be mostly true.
Your own mind tries to tell you something you're not for the sake of protecting your ego and ignore the bad traits. Just imagine someone addicted to cigarettes, they'll convince themselves saying they can quit whenever they want, but really they can't.