Neither President George W. Bush nor anyone else alive is a direct descendant of Franklin Pierce. All of President Pierce's children died young. Barbara Pierce Bush is a distant cousin of Franklin Pierce.
If President Bush is descended from King Charles II of England, it would have to be from an illegitimate child, since King Charles had no legitimate children who survived infancy.
Obviously the easy way to trace your family tree is to run for President.
(.....All of President Pierce's children died young. Barbara Pierce Bush is a distant cousin of Franklin Pierce.....)
Oops, my mistake. Thanks for the correction. Barbara Bush is actually the great-great-great niece of President Franklin Pierce.
http://www.netsrq.com/~dbois/bush.html