kerry descended from the prophet muhammad?

This news is a bit old but I didn't hear about until recently and it seems interesting enough to share. Apparently, according to the genealogists at Burke's Peerage, former Presidential candidate John Kerry is actually a descendent from the prophet.

Harold Brooks-Baker, Publishing Director of Burke’s Peerage, said [...]that, “Senator Kerry, unlike all of the former presidential hopefuls, is a virtual walking United Nations of Christian, Muslim, Jewish and other descent onlrivaleded by his distant cousin, Queen Elizabeth II of Great Britain”.

Such a rich, cultural and religious heritage should give Senator Kerry a great advantage in understanding the complex political issues in the world today, especially those of the Middle East. He is a kinsman of the Shiite Shahs of Persia, the most famous of whom was Shah Abbas I who reigned from 1587 to 1629, and also the Muslim Kings of Tunisia, both of whom descend from the Prophet Muhammad; he is also descended from Alexius I, the Greek Orthodox Emperor of Byzantium who ruled the Eastern Roman Empire from 1081-1118 and via that link is a kinsman of the last Greek Orthodox Emperor Constantine 11th Palaelogus who was slain by the Turks in 1453 while defending Constantinople. Burke's Peerage has documented the SenatorÂ’s kinship with the Christian kings of Jerusalem and Cyprus and through them, the Bourbon monarchs of France including Louis XV, XVIXVIII XVIII and Charles X of France.

It sounds impressive, and in some sense it is, but if you think about it isn't so amazing. It's similar to how if you are in a room with 23 or more people, it is really likely that there is a pair of people with the same birthday. If you stop and think about all the co-incidences which have to happen in order for it NOT to be the case, it makes perfect sense.

In the case of looking at geneaologies, start with one individual. They have 2 parents, 4 grandparents, 8 great-grandparents, 16 great-great-grandparents, etc. in a quickly growing geometric series of ancestors back through the generations. Now, in order for two people to NOT be related, that means that they don't share a common ancestor. And that would mean if you look back at their two geometrically increasing sets of ancestors, they don't overlap. But as you go into the past, in every generation, the number of ancestors is approximately doubling, but the world population of is getting smaller and so eventually it becomes nearly impossible for two people to be unrelated, especially if they are of the same "race". So for example, it has been said that every white person alive today is descended from Charlemagne!