Posters trying to pinpoint blame on this particular single mom are not reading the story very well. First of all, I didn't see any similar problems mentioned as associated w/the 11-yo brother. In fact, even the 11 yo brother has safety issues associated w/his younger brother.
If the Mom or single-mom status was to blame, then we would be seeing two juvenile delinguents run amok. We don't. So stop seeing shadows where there are none.
That simply does not follow, unless you make tacit assumptions like behavior has only one cause, the experience of the two children is alike in every respect, their internal makeup is exactly the same. The older brother may have had more of his early years with a father in the house, and that might make a difference.
Yeah, there's not enough here to blame it all, or even partially, on the single-mom status. There's not enough here to exonerate the single-parent family status from being a contributing cause.
Some kids get hit by cars and recover conmpletely AND they gain a healthy caution about crossing the street without looking both ways. That doesn't show that being hit by cars is never at fault for damaging or killing kids and it certainly doesn't show that it's just as risk-free to be hit by cars as not to be hit by cars.
That some kids do okay coming from single-parent homes doesn't make single parent homes just as good as one parent each of either sex homes.
In this case however, my money is on the 10 year old having some kind of brain damage or personality disorder.