Are there any US presidents not related to King John?

1. The popular claim: “all but one” — where it comes from and who it names

The most commonly cited version of the story credits a young genealogist with tracing 42 of 43 presidents back to a single medieval ancestor and identifies Martin Van Buren, an eighth president of Dutch ancestry, as the lone exception ^{[2] [1]}; that narrative was amplified by outlets and blogs reporting that most presidents can be linked to King John or to shared medieval English stock ^[3].

2. What the genealogy sources actually show — widespread but piecemeal links

Genealogy databases and family-tree reconstructions have produced many medieval connections for a large number of presidents, and journalists and hobbyists have documented extensive overlapping ancestries in the presidential peer group ^{[1] [2]}; Wikipedia’s summary of presidential ancestral backgrounds notes that a majority trace ancestry to colonial-era settlers and European lines, while also flagging exceptions in immigration timing and non-European descent like Barack Obama’s paternal Luo ancestry ^[6].

3. The skeptic’s view: statistical inevitability and methodological caveats

Researchers and skeptics argue that, given population dynamics and endogamy in Europe, many modern Europeans and their American descendants are likely to share medieval ancestors, so finding a common ancestor such as King John among a group of 43 presidents may be unsurprising and not evidence of a special line of descent — and that the significance depends on assumptions about random mating and record accuracy ^[4]. WikiTree and forum discussions emphasize that online family trees vary in reliability and that the meme’s conclusion depends heavily on linking many generations with sometimes sparse documentation ^[5].

4. The exception: Martin Van Buren’s Dutch roots and the limits of certainty

Multiple contemporary reports that popularized the story single out Martin Van Buren as the only president not linked to the Plantagenet line and note his Dutch heritage as the likely reason for the break in documented English medieval descent ^{[3] [2]}; however, those same reports and later commentary acknowledge that genealogical projects differ in scope and that additional archival work could revise connections, meaning Van Buren’s status as a unique non-descendant rests on current, not immutable, reconstructions ^{[3] [4]}.

5. What can be responsibly concluded from the reporting

Based on the available reporting, the simplest answer is that many reconstructions assert nearly every president except Martin Van Buren descends from King John or shared medieval English ancestry, but experts and skeptic-analysts caution that such broad claims are subject to methodological limits, incomplete records, and statistical expectations about shared ancestry in European-descended populations; the reporting does not provide an unambiguous, peer-reviewed proof that absolutely every president (other than Van Buren) is a documented descendant of King John ^{[1] [2] [4] [5] [6]}.