I do not know, but I’ll tell you what I do know. I grew up in a gang infested area, and my observations have yielded these conclusions. How to stop the gang problem:
Provide an equivalent education to all, no matter the economic condition. With a proper education comes actual opportunities at a career and a decent life.
Discrimination against minorities and immigrants must change. Having the majority of your countrymen think you are less than, and not as capable not only wears on the psyche, but creates a distance between people. Why would anyone want to adopt the values of those who think they are less than capable.
At this point in time poverty is a vicious cycle. Those in poverty have children; those children receive deficient educations, they are bombarded with images of themselves as criminals, drug addicts, abusers of the system, as less than, and not belonging; these kids grow up with little opportunity and a feeling of alienation, and they reach out to the only security they can find: gangs. As these kids grow up, they produce children with the same experience. The cycle continues. Until the situation changes, gang culture will continue to thrive.