My family takes geneaology very seriously. The link to the Merovingian line is very sketchy. The link to Charlemagne--uncertain. The link to Jesus? Laughable. The further back in time you go, the reliability (not to mention availability) of information for genealogical purposes becomes dubious. Even if the link to the Merovingian line were to be found true, then there is still the extremely dubious question of how the Merovingians could possibly be descended from Jesus. As far as I know, there has been absolutely zero evidence that such a genealogy connecting the two exists. It's all assumptions.
Over 20 US presidents also descend from Rollo the Wolf. So, there is roughly 20 more familial lines that can claim this dubious heritage (Bush Sr and Bush Jr counting as just one). Then you have common everyday people like myself who are also descended from the same line and in my family line alone, there are at least a dozen name variants within about 600 years. Take those 20 presidents and a dozen family names tied into their own lines (basing off of the example of my own line) and you have around 252 different family surnames running around with this so-called "sacred blood". And that is just in the US, counting the presidents descended from Rollo....It doesn't even include the multitude of average everyday people like myself. Getting the picture yet?
These people who claim some sort of superiority because of a highly dubious claim are simply quite full of it. They are nothing but self promoting charlatans trying to gain power. There are probably over a million people out there with their same origin of bloodline (and not the dubious jesus/merovingian link!). Does it make all of us special? Absolutely not. Even if there was an ounce of truth to it, I'm certain that it would be several million descendents in the course of 2000 years...
And yes, inbreeding does vile things.