Well, my parents first left us when I was 16 and my brother was 14. We were both sensible and managed just fine. We even cleaned the house after we had had the wild party!!
Deanne was 15 when she decided she no longer wanted to come on holiday with us..so she stayed behind and she was fine. Gav decided this summer aged 15 that he didn't want to come back to Gozo with us..so he stayed behind..but trusting him slightly less to fend for himself, we arranged for him to check in with my parents every couple of days..he was totally fine and even managed the food budget that we gave him for the household stuff. He had done shopping for our return and fed and watered the animals as well as hoovering etc and generally keeping the house tidy. We left him again for 1 night a couple of weeks ago while we went up to Seahouses to go scuba diving with the seals and all hell broke loose!!!! He had a bit of a party that was gatecrashed and a so called friend of his decided to burgle our house..the neighbours didn't realise that Gav was home, phoned the police and reported the burglary and the police came screaming round and raided the house of the little old lady across the road...needless to say, Gav was in a lot of trouble, his so called friedn ( who we even took on holiday with us) is barred from our house
forever for deciding he would burgle our house, and then denying it after being caught!!
The general rule i would apply is how well you know your children, whether there is a support mechanism around them just for extra reassurance and what other risk factors would apply. If you can satisfy all of those, then base your decision on that.
oh and FWH.anyone under the age of 18 is classed a minor..