[technotony]

It's way less than that. They scan SNP's, of which there are about 10 million in total. So only 0.3% of the human genome varies between all of us. I think they only do the 602,000[1] most common SNPS, which is only 0.02% of the genome though they might do a few more.

A SNP is a Single Nucleotide Polymorphism, ie places in the genome which vary from the reference human genome by change of one base pair. [1] https://www.snpedia.com/index.php/23andMe_v4_differences