My brother - A troubled teen

I live in Hauppauge, a fairly decent place to raise your children. In fact most would say it is more then decent. When we first moved here from Florida when I was 8 years old my parents worked hard to be able to raise their children in a town that they thought would enable us to grow up surrounded by the good morals they attempted to instill in us. My parents divorced when I started my freshman year in high school. My sister Amanda was a sophomore and my younger brother Justin just started middle school (6th grade), a time when a father figure is detrimental. The year my parents divorced was the year we also divorced our dad. I now am old enough to realize that my dad was to heartbroken and distraught to care about anything else, yes even his old kids. My sister and I went through the typical phases , cries, talks with mom and friends, etc. My brother being a typical male stereotype held all of it in. It started with fights at school and no longer wanted to play football. This carried on into high school were he decided he just did not want to even go to school. Now, as a junior he is reluctant to even get his permit to learn to drive which leads to his lack of motivation to work to even get a set of wheels. I have been acting as the strict "mom" towards him in my family because my mom has always been a push-over. He causes her a great deal of stress and it upsets me. She spends loads of money on his dirt bike and other gadgets that he winds up selling for the green stuff. This angers me very much because I worked hard to be able to buy my first car at his age. We all know the importance of a father in a young boys life. Especially because my brother is surrounded by 4 woman, one of them being our dog, Lily. I can't help but wonder to what extent is the lack of father figure that important? Yes maybe the child will be problematic, but could my father be the one to blame for it all? Will he ever grow out of this phase? Are their other factors causing it, maybe his experiences in middle school or the fights we used to have as kids? I guess I will never know how my sister and I seemed to make it through okay and he did not.