What's a statistically proven fact that nobody wants to hear?

The lead-crime hypothesis proposes that the United States crime rates have dropped, in part, because of lower levels of lead exposure in the environment. No, it's not fewer pencil munchers (pencils don't use lead paint any more and there has never been lead in the actual graphite). No, it's not necessarily less lead paint eating. The main driver of the lower lead levels is elimination of leaded fuels.[1] This hypothesis stands as an alternative or supplement to other explanations including gun proliferation, the United States war on drugs, the legalization and subsequent increase in the number of abortions, or increasing rates of imprisonment and capital punishment.[2] [3] Demographic change - specifically, a reduction in crime-prone young males - was once proposed as a cause of the drop and forecast to cause increased crime in 2010, but it did not.[4] However, like all other hypotheses about the cause of the decline in crime rates, it may very well be wrong. Sure, if you squint just right, it might explain a long term drop in the crime rate, but it says nothing about prior increases in crime. And maybe, just maybe, lead is a factor but not the only factor.

http://rationalwiki.org/wiki/Lead-crime_hypothesis

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