Went out today to buy a pair of shorts and pyjamas for DS aged 13 (to supplement holiday wear).
Went to two Tescos, Sainsburys and Next.
Absolutely nothing for boys beyond the age of 12.
I can only assume that lads continue to wear clothes bought for them when they were 12 until they are about 17 and start to fit adult clothes. This would explain all the 'cropped' trousers and tee shirts I see!
It would also explain the obsession with xbox etc. They need something to do until they can find clothes that fit and they can go out into the world again!