Childhood Bullying and Depression

I've begun to wonder recently, which came first - the chicken or the egg? Did the bullying cause my depression, or contribute to it to a great extent? Or was I bullied because my depression and shyness made me a likely target? I would say that an argument could be made both ways, but I tend to think that I was susceptible to depression because of my personality and my parents' divorce, and that being bullied is what made it manifest.

Some people will tell you that bullying is harmless, just kids being kids. Not true. I'm here to tell you, as a victim of many years of bullying, that it's not harmless. It can make a child's day-to-day existence a living hell. Is that what childhood is supposed to be like? And there is no question in my mind that it can lead to depression, which absolutely is not what a child should be living with.

Links
Bullied Children at Risk of Depression, Antisocial Behavior
Study on Bullying Indicates Bullies are "Popular"; Victims Suffer, are at Risk for Suicide