By Amy Feldman

By Amy E. Feldman

PHILADELPHIA (CBS) – How young is too young legally to let a kid walk home alone?

Two Maryland rocket scientists are under investigation for child neglect for letting their kids, age 10 and 6, walk home alone from a park a mile from their home.

Obviously, they’re no rocket scientists. One is a physicist and one is a climate science consultant. But the laminated note they gave to their children in case of an inquiry makes many parents wonder about their intelligence. It read: “I am not lost. I am a free range kid.” They argue that kids benefit from gaining independence and confidence.

The police are investigating whether so-called free range parenting is actually just child neglect. Is it?

There is no federal law that governs the age at which a child can be left home alone, much less how far they can wander from that home – and even most states are silent on the matter.

Among the states that do have a minimum age at which you can leave your kid home alone, Maryland has the lowest age of 8 – and under that a child must be left with someone at least 13-years-old – so the parents here may have broken the law leaving a 10-year-old alone with a 6-year-old.

The National SafeKids Campaign recommends children not be left home alone until age 12, but urges parents to consider both age and maturity because, while children ages 7 to 10 generally can’t self regulate for an extended period, they may be able to be alone in a predictable routine and environment like home after school.

In any event, while parenting is certainly more art than science, letting a child walk home alone isn’t just a test of the child’s maturity but the safety of the strangers around them.

So whether or not it’s against the law, most would say ‘you can be free rang, right here where I can see you.’