People need to study history, and perhaps their own family tree...
Second cousin marriage was very common all through history. It's not ideal, but it's not really bad like first cousin or sibling which the above replies are making it out to be. It is genetically far apart enough to not be incest.
For those of you who do not know, you can search "cousin calculator" online and you'll see the chart explaining the links. It's not a very close relation, you have ONE great-grandparent in common, that's it.