The Grail Bloodline is a bloodline that is allegedly descended from King Arthur who was supposedly descended from the marriage of Jesus Christ with Mary Magdalene. There is absolutely no evidence to substantiate those claims. There are no bones. There is no gravesite. There is no marriage certificate. The only references that the writers of The Holy Blood and the Holy Grail can find that give any sort of credence to the “legend” are from the Grail Romances written by Wolfrem, which allude to the Fisher Kings and King Arthur who was a historical figure. The bloodline exists but it does not come from Jesus.
An excellent website which details the genealogy of the Sinclairs and the Stuarts is: 
While it doesn’t mention every generation it gives enough information to be able to follow the thread. It has helped me to piece together how my family fits in to it all. Because it involves many generations I have had difficulty verifying some of it, but this particular page has helped enormously. The descendants of King Arthur only “appear” in the 1300’s however Laurence Gardner in a lecture he gave on the Grail Bloodline stated that my ancestors the Princes of Aquitaine were descendants of the Messianic (The Messiah) bloodline.
In the early 5th century, Jesus and Mary’s descendent Fisher Kings became united by marriage to the Sicambrian Franks, and from them emerged a whole new reigning dynasty. They were the noted Merovingian Kings who founded the French monarchy and introduced the well-known fleur-de-lys (the ancient gladiolus symbol of circumcision) as the royal emblem of France. From the Merovingian succession, another strain of the family established a wholly independent Jewish kingdom in southern France: the kingdom of Septimania, which we now know as Languedoc. Also, the early princes of Toulouse, Aquitaine and Provence were all descended in the Messianic bloodline. Septimania was specifically granted to the Royal House of David in 768, and Prince Bernard of Septimania later married a daughter of Emperor Charlemagne.
Merovee (415-558), King of the Franks (Germans), was the first of the Merovingian Kings. He believed he had two fathers; an earthly father and another who “came out of the sea”. (It sounds like the nephilim to me.) Because of this ‘dual blood’ the Merovingian Monarchs allegedly had mystical powers, being ‘occult adepts’ and on a par with Merlin. Another influential person was Rollo who was the first Duke of Normandy and an ancestor of William the Conqueror (and of mine) was himself descended from Odin who was a Norse god. It is descendants of these bloodlines who are in high places of power as either royalty or heads of government or hidden elite families. Not only is this bloodline not from Jesus but neither is it from God. It is true that these people are also descended from King David but the bloodline has been polluted with the inclusion of the blood of fallen angels i.e. Lucifer. It has come as quite a surprise that I am a part of all this but thankfully, Jesus has revealed it to me over a period of time and has shown me things on a need to know basis only because it has been really difficult to understand and comprehend.
This bloodline typifies the influence over nations today and in a perverse way “legitimizes” Satan’s authority to rule. His dominion has only ever been because he deceived Adam and Eve into yielding up the dominion God gave them at Creation and he has continued in this deceptive vein to today where these people believe that because they are descended from King David, they have “the sure mercies of David” on their side because of the forever covenant He made with David and his sons through a covenant of salt. (1 Chron. 13:5).
 http://www.bibliotecapleyades.net/biblianazar/esp_biblianazar_11.htm  The Holy Blood and the Holy Grail by Baigent, Leigh & Lincoln, P. 254