Student behavior is affected by many factors.
Those arising from the home - family income, parents, family
culture and attitudes towards discipline, etc.
Those from the school - school culture, staff and principal,
etc.
Get enough children with similar factors together and you'll find
the school will produce students with similar tendencies thus the
resulting reputation.
But basically, I don't believe there can ever be 100 % anything
when it comes to matters relating to people , e.g. 100% involved in
BGR. I don't think that's possible.