I re checked the DeMarce source,  I see it says it was a a personal Essay,  I do not see anything showing it was published or peer reviewed, or anything of that nature.  I am not exactly sure what the website hosting it is other than it says "A Comprehensive Collection of Online Published Articles".  On that website that was used as a source is a Article on Melungeons which states "Conclusions
Solid genealogical study of Melungeon ancestry overwhelmingly leads to a simple conclusion. The primary genetic makeup of Melungeons - that which gives them their Melungeon physical characteristics - comes from certain Native American tribal genetic lines. Careful genealogical research, working backward from universally accepted Melungeons, shows their ancestral lines go back to Native Americans. The truth may not be as exciting as having an unsolved conundrum but the truth is that Melungeons almost certainly are descendants of the intermarriage of Native Americans with old-world colonists. This isn't an opinion. This is a scientific conclusion. They aren't Portuguese. They aren't Turks. They are Native Americans."  The Melungeon Mystery Solved by James S. Elder
http://www.theworldthrumyeyes.com/conclusions.html 
http://www.genpage.com/genealogyDNA.html

As you can clearly see it is on the same website that the Virginia Demarce source was gotten from.  However as stated I do not see how Genpage can be used as a reliable wikipedia standard source.  So that does need to be reviewed to see if the source can even be used on wikipedia.