Bad parenting may have a tiny role to play but the overall reasons are far more complex than that. What follows is a comment I have posted on most questions or hubs on this theme...added here in case you haven't read it yet. It may resonate with you in "classless" America!
I think the rioters stole stuff simply because they could. They didn't care about the consequences for society at large, they only cared about themselves and perhaps their circle of family and friends.
Unfortunately, this attitude of screw society, screw the community, screw the country because it's all about 'me', 'my' and 'mine' has pretty much been encouraged in this country for the last 30 years or so from the top down.
It manifests itself in very different ways in our diverse country.
In the banking system we see managers of failed nationalised banks paying themselves huge unmerited bonuses at the expense of the tax payer simply because they can.
In our parliament we saw our politicians inventing a set of rules designed to allow them to abuse the expenses system to claim for plasma TV's and tens of thousands of pounds for 'renting' the spare room of family members, and using these monies for speculating on the property market and then dodging the tax on the profits. MPs certainly wouldn't steal a plasma screen TV in a riot, not when they could just simply walk into John Lewis, order it to be delivered to their home, and stick in an expense claim for it.
In the police force we hear claims of police selling confidential details about the royal family to gutter press hacks simply because they could and thought that they could get away with it.
As for the media we hear claims of editors ordering that private investigators hack private citizens phones, simply because they can and think they can get away with it.
We hear of celebrities and the super rich dodging the taxes the rest of us have to pay at a time when services for the very poorest are being cut, simply because they can.
And in the underclass what do we see. Wide spread stealing and looting, again simply because they don't care about society and because they can.
Something has gone very wrong with this country. But to think this corruption is confined to one section of society is wrong. And I think we all need to look within.