Global DNA variation of humans is about 0.5% of genes.[1] So I think that implies an average Brit shares 40% of that 0.5% with the average French. 0.4*0.005 == 0.002 -&gt; 0.2% of the genome.<p>Funnily, as a casual observer I would agree that the English language is 40% French (vocabulary) and 26% German (structure).<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Human_genetic_variation" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Human_genetic_variation</a>