In yesterday's New York Times there was a very interesting article called "Who's On the Family Tree? Now It's Complicated" about how complex families have become. The article digs into the issues of modern day families that include half-siblings, step-siblings (not that those both haven't been around for a very long time) sperm donation, surrogate mothers, same sex couples, etc. It seems like future genealogists are going to have their hands full trying to keep track of it all.
One paragraph in the article really struck me:
http://www.nytimes.com/2011/07/05/us/05tree.html?_r=1&src=tptw : 2011."Who's On the Family Tree? Now It's Complicated." The New York Times, 4 July 2011. Online version.