By contrast, McCain -- himself a veteran and the son and grandson of two Navy admirals -- has two children in the military. Nineteen-year-old Jimmy is a Marine and 21-year-old Jack is at the Naval Academy. The fact that his sons are willing to fight a war McCain has vowed to try to win lends moral credibility to his words. He wouldn't ask others to do anything he and his family wouldn't do. (Joe Biden, who recently withdrew from the presidential race, also has a son in uniform. That he would be willing to serve in a war his father disapproves of shows that service trumps politics in their family and made Biden, like McCain, a compelling candidate.)
It will be easier for Americans to take the next president's inevitable call for sacrifice seriously if that president's children are in the military. We need a president who can honestly say: "We're all in this together."
http://www.washingtonpost.com/wp-dyn/content/article/2008/01/08/AR2008010804437.html