In genealogical terms, the number of ancestors doubles every generation — ten generations back, you have more than a thousand ancestors.

Going back three hundred to four hundred generations, you effectively have an ancestor in every population that existed in a geographic area connected to your ancestry.

What the ten percent figure means is something different: approximately ten percent of the genetic material carried by modern white British people is most similar, in its specific combination of variants, to the variants found in WHG populations like Cheddar Man.

In the language of population genetics, WHG-like ancestry constitutes about ten percent of the ancestry proportion of modern British people.