The next thought related to this is that our childhood thoughts and "echoes" are stronger than the ones we create now. And if we start trying to change the frequency of the echoes, discord happens!
Our minds need harmony. We need to be in accord and consistent throughout. For example say you grew up following the teachings of the Koran. You then come to America and learn about Jesus. You will have a very hard time becoming a Christian when there are so many different chords and melodies in your head that clang against what you have vibrating in your head already.
I think it's possible to change but it's going to cause a lot of discomfort and a lack of peace for a long time.