Hobbits mature at 33
22 in Hobbit years is a child
NOT LEGAL
> Most Hobbits lived longer than Men, a race of which they might have been an off-shoot. The average lifespan of a Hobbit was about 100 years, though it was not unusual for a Hobbit to live as many as three decades beyond that. The time at which a young Hobbit matured and was accepted as an adult was 33, compared to a Man's 18 years.
http://lotr.wikia.com/wiki/Hobbits#Age_and_appearance