I have a step brother who's a bully and won't listen to anyone aside from his mother. They had them checked by a child psychiatrist before but was told that we doesn't have any disorders. I myself is having a difficulty dealing with him. How can I teach him to act properly in front of others and to stop doing what he used to do like bullying and nagging at us most of the time?

What's your brother's age? My advice is don't let him get the best of you. If you plan to change him, conquer him. Reverse psychology works! Try to be his friend, his confidant. In that way, he will trust you and believe in you. That way, you can influence him to change. Just don't get fed up of befriending him and reminding him of what he should do. In other words, "utuin mo" :)