The Merovingians - Red Hair?

I've just came across this article about the Merovingians;-
http://www.21stcenturyradio.com/merovingian-twyman.htm

It states that the Merovingians had "long red hair." I've heard this mentioned before online. Is it true? What's the source for it?

If it is true it would be really fascinating.

The Denisovans Didn't Have Red Hair

Just read that the Denisovans, a recently discovered ancient species of human found in Siberia, did not have red hair.

http://news.cell.com/story.php?title=denisovans-did-not-have-red-hair