I think there's just a lot of generalisations there to be honest and while I get its based on personal experience, that only counts for so much.
It's not just 'black kids stabbing each other'.
Just because you get 2 black kids attacking you when you're younger doesn't mean that every black kid (with or without a father/father figure) ends up in jail or in a gang or committing crime.
I agree society and culture has to change - having said that, taking police off the streets does have a huge impact in how society can behave. The correlation is clear from where I've worked for the past 4-5 years. In the start of my job, we had a PCSO or 2 covering various districts and wards of the town. About 4 or 5 covering the town and being visible in the areas. More to the point, they would actually converse with the kids who would cause petty crimes and they would know the families and the history behind the kids being little shits. And when the cuts hit? There's one or two PCSOs covering the whole of the town. How is that even practical to manage? Their time is taken up by crime that happens all over and the impact of their work is lost. Obviously we want to eradicate gang culture (which comprises of white, blacks, Asians, not just one or the other). So I would disagree when you say 'no amount of Police will stop this'. I think more police on the streets, even in a PSCO role, would have a positive effect. Purely because it's worked before until the cuts came in and then when they did, there's less for a Police force to spend on that particular role. Even higher up the chain - there's just simply not enough PCs to manage large towns/cities. So as a result, I think it's quite obvious that crime rates increase and it's not just because of 'society'.
The culture in schools I agree should change and be directed towards making kids more active and promoting good exercise. To be honest, I don't work in a school and I haven't been back in one for years so I couldn't really say what kind of schemes or initiative there are currently in place to promote it but I think it's imperative for any government to influence in future the importance of getting kids active. Pushing the idea of physical activity and allowing a certain time in the school day for it is just important as being academically sound, too.
Mental illness is a sensitive subject - it's too easy to say 'physical activity makes you feel better' and clears your mind. Especially when you look at the amount of athletes/sportsmen/sportswomen that are literally physical every single day of their career and still suffer depression/anxiety etc. Of course there's different pressures in various walks of life but mental illness can't be treated so easily as just being a physically active person. There definitely must be more investment in support services for mental illness. I'm not talking about those who feel a bit shit one day. I'm talking severe cases where there's mental breakdowns and genuine mental concern. I have one friend who suffered a breakdown and had to wait 99 days to be seen for her first appointment. That's not on.