Mazo de la Roche 
The Two Saplings 

This novel tells the story of two families, English and American, on whom circumstances have played a strange prank which might have had unhappy consequences.
As an experiment, they send off their sons to see the other’s country, but then war intervenes, and the story of the Wyldes and the Rendels shows the problems and the promise of Anglo-American relationships now and for the future.