True, each of us is given choice in what path he will going to follow,. On large part our experiences, both bad and good moments in our life, our own thoughts and societry are forming our individuality influencing in what kind of person we are going to grow in.
As humans we are not perfect, far from it. We are capable of doing some of most bestial things with no mercy and empathy for anyone, but we are also able to do most noble, positive things someone could think of as well showing lot of support, understanding and help to those who are in need of it. There is saying "each of us carries in himself light and dark side, it only depends on us alone and strength of our character which side is going to prevail and what kind of person we are going to be"(or something similar, sorry English isnt my native language). Sometime unfortunately some people choose wrong path not being strong enough and stable to resist negative temptations or because of having horrid life losing faith in good deeds becoming corrupted or bad, but even for those there exist chance to repent and get back on right track if they truly mean it and reform themselves trying through good things to at least partially fix negative things they done before.
Speaking of humans as whole we may sometime do wrong thing, act selfish, conceited or hateful, even most mature and wisest people pit there are prone to do mistakes, lash out on others when having bad day or be unreasonable, cynical and mad for no reason but whats truly important is for each individual to be able to recognize flaws and negative impact on his way trying to fix things up and work on himelf that such situations happen less poften.