The earnest discussion that follows this question is all about finding the connections, however tenuous, between 'us' and the rest of the world.
When England plays Italy I say that we will 'vote' for Italy: "Dad's grandfather was from Sicily."
"But" interjects Mr9 "my best friend's Dad is from England".
This morning it is Croatia v Mexico. My heart is with Mexico, because I know that good friends of all four of my children will be cheering them on wildly from their homes in California. Then I remember that one of Mr14's best friends is about to visit Croatia for the first time, to meet his mother's extended family.
When Australia plays there is no argument. We are Team Australia. And the same applies when America plays.
My youngest - like the rest of us, a dual citizen - cannot keep things straight in his own mind when the country of his birth or the country he now lives in play.
"Is Australia winning?" he asks during the Portugal v USA match.
"No, America is playing, not Australia," I say.
Australia and America are in his mind interchangeable. They both represent and bring forth the feelings associated with the places we call "home".
My son's loyalties are not divided, nor are they in competition with each other. In fact the opposite is the case. Like immigrants the world over, he feels more connections not less, and this is in my mind something to be celebrated.