His sister Maggie had a romantic interest in Indiana Jones. Sean was initially very skeptical towards the young American, but eventually Sean and Indiana became friends.
In the 1960s Sean Lemass became the Taoiseach (head of the Irish goverenment). During this time Lemass developed Ireland from an agrarian society into a modern industrual and service lead economy. To this day Ireland is leading force in pharmasuticals and IT.