Seeking YA book written between 2008-2015-ish, about a large family where everyone is hyper-competitive and wants to set the most world records. They’re continually in battle against other hyper-competitive families, all except one son who the family kind of looks down on when he is nice/fair.
It’s considerably older – the books were published between the late 70s and 2001 – but I wonder if you’re thinking of the Bagthorpe Saga by Helen Cresswell? There are ten books, the first one being “Ordinary Jack”, and fit the description very well. There are four Bagthorpe children and Jack is the nice, non-outstanding one; the others do all try to set world records (some of them quite weird) with the hope of getting into the Guinness Book of Records. Their parents are an eccentric screenwriter and an agony aunt. It’s mostly their cousins with whom they feel they are in competition. The books are comedies, but quite dark for children’s books!
https://en.wikipedia.org/wiki/The_Bagthorpe_Saga
I didn’t realise there were as many books as this – I think I read up to about book 7 in the late 80s / early 90s.
Hmmm, no, similar concept though. The ones I read were definitely more recent. They were Amazon Recommends on other YAs from around 2010-ish. The family was far nicer sounding, just really hyper-competitive and focused on winning really random things.
The Fantastic Family Whipple by Matthew Ward?