IF you want to understand just how miserable a childhood can be, 16-year-old “Jane Doe” is a good place to start.

That’s what the authorities in Connecticut call her to protect her identity. She was removed a few days ago from an adult prison where she had been confined by herself for two months — not as punishment but because the state said it had nowhere else to put her that would be safe.

Now Jane is in a girls’ detention center in Middletown, Conn. She’s one of almost 70,000 American youths incarcerated on any given day — and a reminder of how ineffective our programs for troubled children are.

Like many detained kids, Jane has been through hell. Because her father was in prison and her mother was a drug abuser, she was raised by relatives. At age 8, she says in an affidavit provided to the courts, her cousin began to rape her anally, causing her to lose control of her bowels.