Since we are all related, this is really not so surprising
Pedigree Collapse or Consanguinity
Some people fall in love and marry their childhood sweethearts. Others marry their neighbors. And still others marry their cousins. Our family is no different than yours. You are invited to take a look at how this works and some specific examples.
If you wish some additional light reading on this topic there are a couple of great examples here: http://tinyurl.com/ptokrgv and here: http://tinyurl.com/hfv77d9 and this article discusses the phenomenum as it applies in the United States http://tinyurl.com/mwg23y2.
- All Married Cousins
This is a list of all known cousins married to cousins. It is important to note that there are undboutedly numerous instances of others that have not been flagged.
- The Surprising Truth About Cousins and Marriage An excellent video about the somewhat unique topic of cousins and marriage.