Clue #2: The buildings in the background are distinctly of another land - Europe? Russia?
Clue #3: The boy apparently is a fan of Ang Lee's Brokeback Mountain. He likes Ennis!!
How'd I do?
Turns out they are brother and sister (twins) and they are in Russia!! Yay, I was right! But since this book predates Brokeback, I am embarrassingly wrong on the last clue. Does he like Dennis? Dennis who? It can't possibly say I LIKE TENNIS, can it? That would be such a lame statement, to merely like tennis. Who has such a lukewarm feeling about tennis? I, for one, loathe it.