Here is an article suggesting that the recent decline in crime

[conuly]

Correlates neatly with the decline in lead in the environment, and is related.

http://www.motherjones.com/environment/2013/01/lead-crime-link-gasoline

The reason I've most often heard for the declining crime rate is "abortion of unwanted babies!!", and while that argument seems to make sense, it starts to fall apart when you realize it does not answer the necessary OTHER question, namely, "what caused crime to go up in the first place?" This explanation does, though that does not guarantee that it is correct.

Comments

[elenbarathi.livejournal.com]

"If abortion rates cause crime rates to fall, crime rates should start to fall among the youngest people first and then gradually be seen lowering the crime rate for older and older people. In fact, they argue, the murder rates first start to fall among the oldest criminals and then the next oldest criminals and so on until it last falls among the youngest individuals. Lott and Whitley argue that if Donohue and Levitt are right that 80 percent of the drop in murder rates during the 1990s is due solely to the legalization of abortion, their results should be seen in these graphs without anything being controlled for, and that in fact the opposite is true."

It probably is somewhat of a factor, because people who don't want children don't make great parents, but not no 80%. Lead? Maybe a factor, but unless there's some actual research to support it, who knows?