U.S. Senator John Kerry and Brice Lalonde, the French-born coordinator of the United Nations Rio + 20 summit conference on sustainable development ,which got under way this week, have a lot in common. Among other things, they are first cousins, a fact widely reported when Kerry ran for the U.S. presidency in 2004.

And now both of them are involved in pressing for the success of a radical U.N. agenda for climate change that seems to be faltering in the face of global economic crisis.

Lalonde, 65, and Kerry, 68, share maternal grandparents; Lalonde's branch of the family bought their French estate in the 1920s and, according to news reports he and the future Massachusetts senator played together as children.

Both were involved in cutting-edge political causes in their youth, Kerry as a decorated U.S. Navy officer turned vociferous anti-war spokesman in 1971, and Lalonde as leader of the French university student's union in 1968, a year of near-revolution in France, and subsequently as a militant supporter of Greenpeace.