All Rooney's people from both sides are Irish decent, think the grandmother's name is actually Fitzsimons(?) and that's on his Mum's side, he has 26 county roots on his father's side.
As for the Keowns, I know people in London who knew the family and they were pillars of the Irish community over there, there was a lot of surprise and disapointment when he declared for England.
Agree with your last point, I have 2G mates who consider themselves totally Irish, others who support Ireland and England (cop out imo) and others who follow England, as you say, each to their own....