The 17 year old may well be from a previous relationship. Has never come to terms with the new parent in their life. Nose pushed firmly out of joint by the arrival of 3 younger siblings that get all the love the 17 year old feels they missed out on. Family go on holiday in an ill-judged attempt to look normal. One perceived slight against the 17 year old and all hell breaks loose. 17 year old becomes unreasonable, parents become unreasonable, younger siblings become unreasonable. Family holiday ends in media spectacle and slightly shamed faced everyone finally returns home. Card from management firm of Jeremy Kyle slipped through letter box 
