I thought I had it bad, being ultimately responsible for the well being of two human beings. Sadly, Obama lost his grandmother today. He's walking into the POTUS position without any of his prior guardians. He's responsible for his family (with Michelle) and soon the entire free world, without support from those who have historically cared for him.
OK, maybe its a bit of a stretch to say he's responsible for the entire free world; but, he sure has a lot of responsibility to it.