Boys in US jails sentenced to life without parole

Article here. Excerpt:

'(CNN) -- It began as horseplay, with two teenage stepbrothers chasing each other with blow guns and darts. But it soon escalated when one of the boys grabbed a knife.

The older teen, Michael Barton, 17, was dead by the time he reached the hospital, stabbed twice.The younger boy, Quantel Lotts, 14, would eventually become one of Missouri's youngest lifers.

Lotts was sentenced in Missouri's St. Francois County Circuit Court in 2002 to life in prison without parole for first-degree murder in his stepbrother's stabbing death.
...
Lotts is one of at least 73 U.S. inmates -- most of them minorities -- who were sentenced to spend the rest of their lives in prison for crimes committed when they were 13 or 14, according to the Equal Justice Initiative, a nonprofit organization in Alabama that defends indigent defendants and prisoners.
...
At the time of the crime, Tammy Lotts said she left her children for several days with her husband to get high on crack cocaine.'

So why wasn't Tammy Lotts and her husband put away, too? Maybe her husband was (the story doesn't say) but it looks like she wasn't charged with anything.