Why did Cain kill his brother Abel?

Cain was first generation offspring of created man & woman. There was no one else to speak to Cain about his crime against his brother. At the time, God still spoke audibly to man.

As the number of man grew, God was selective to whom he spoke aloud.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.