Researchers say despite age limits on voting and drinking, there's no set time for the onset of adulthood.

"People don't magically mature at 18, it takes some people a lot longer."

New guidelines are being established redefining the age between 18 and 25 as late adolescence.

Scientists found hormonal and brain development continue in your late teens and early twenties.

"The idea that suddenly at 18 you're ad adult, just doesn't quite ring true."

Researchers also warn our "extremely tolerant western culture" may be doing more harm than good, by coddling the immature.