The Science Behind 15th to 50th

How Far Back?

A first cousin shares grandparents.
By the time you’re at a 15th cousin, you’re tracing back about 16–18 generations—roughly 400–500 years.
A 50th cousin would mean going back ~52 generations, or about 1,300–1,500 years.
That’s when written records fade, but DNA keeps the receipts.

Each generation halves the DNA you share with direct relatives.
By 15th cousins, the chance of sharing any detectable DNA is extremely low—most won’t show up as a “match” in genetic testing.
But here’s the kicker: once you go back far enough, everyone’s family tree overlaps.
Mathematically, by 50th cousins, you’re essentially related to everyone on Earth if you go back to common ancestors (scientists call this the “Most Recent Common Ancestor” problem).

Geneticists estimate that all humans share common ancestors within the past 2,000–3,000 years.
That’s why “15th to 50th cousins” isn’t just poetic—it’s biologically accurate. We’re all kin, just spread out on the family tree.
This is the science behind the “we are all cousins” idea you’re promoting: genetics, population math, and history converge to prove that we’re literally one giant extended family.

Stay updated on our progress and be the first to know when we launch!