Quoting Heraclitus "There is nothing permanent except change" ... I know it doesn't explain your question but it actually does.... 
Another quote, this time from the Holy Bible, Corinthians 13:11 "When I was a child, I talked like a child, I thought like a child, I reasoned like a child. When I became a man, I put the ways of childhood behind me"....  
Some people change, while others evolve... 

Yes, you said it right, but stop writing Franco-Arab!! I bet that you can't write Arabic letters, Gagan! :)

Of course, they don't always change to bad, but the majority do that! :))

Have a nice day!

<em>Shiamaa their characters is your mean or their manners and behavior? Such as soucial behavor? And do you mean that why they change from good to bad and you know sometimes the mean of good and bad are diffirent according to cultures. I never mean that  values are diffirent , no , I just mean most of times our definitions of good and bad are not the same.</em>

Why People Change....

Cause changind is what separates the living from dead. It's a part of Life. The Cycle of Universe...

Plus People change coz we are learning new things and To Learn is To grow.

Plus I have a question for U too.

Andi sawaal leeki kaman :p (did I say it correct)

You said

"I'm serious. And I exactly mean changing to bad!!"

Do You feel ppl always change for the worse?

Coz I don't think so :)

My dear it is natural that people have mood swings. All people want something in a few minutes and then no longer want..