Why Does the author provide a flasback to general zaroff's childhood?

The author describes Zaroff's childhood in order that we might better understand his past..... the reasons he believes himself entitled to do as he pleases, the reasons he feels free to entertain himself as he wishes, and possibly to give us the necessary background as to why Zaroff has no respect for human life or remorse for his actions.

When I was only five years old he gave me a little gun, specially made in Moscow for me, to shoot sparrows with. When I shot some of his prize turkeys with it, he did not punish me; he complimented me on my marksmanship.