Jealousy

Ok so I have to wonder where envy and jealousy come from.  I understand that it is a state of mind, but I guess I wonder because I have never really been one to feel it much.  In my entire almost 40 years alive I can recall maybe 5/6 incidents, my heart is numb and confused on the feeling I suppose.

Jealousy can be for many reasons and make people act, feel, and say silly things.  But when it becomes a problem when people are invading you privacy what do you do then?

Those who know me well know why I ponder on this.  Stupidity in my eyes can come hand and hand with the green lil monster.  I think when people they should ask themselves-why do I feel this way? why are the people that are making me feel this way doing the things they do? what have I done to make it all happen? why am I so angry? what are my valid points?

If anybody has some insight on this please help me understand.