John and Phillipa Gaunt have a rich father and a glamorous mother, live in a swanky New York home in a wealthy neighborhood, and are lucky enough to be twins without looking exactly like each other. They have their own share of troubles though: they get their wisdom teeth by the time they are twelve and they discover they are not entirely human. They are djinn. As in "genies".
Think Indiana Jones blended with Harry Potter backed up by National Geographic. There is fact, fiction, action, and good humor, and a grumbling English butler. It has been fun reading this series. There are some moments of mild rude humor (think about what makes little boys laugh) but nothing objectionable. You don't have to read every book in the series to enjoy any individual book; you aren't overwhelmed by "backstory recaps" but you get enough that you could just about pick up anywhere in the series and be just fine.
Good stuff for summer.