Interestingly, if you use 23andMe's genetic analysis service, it'll tell you how much Neanderthal DNA you have. The average European has 2.7% (I have 3.2%).
Has there been any sort of serious audit or quality review of the 23andMe service? I'm dimly curious but would at present guess it's mostly a load of nonsense, and who even knows how replicable their results are.
I'm not entirely sure, I mean, from my level of understanding it could all be relatively faked data and I wouldn't know any different. They claim they do quality review[0] and you can compare them to some of the competition[1], and they don't offer anything except genealogy records and your results in a big file you can download. You can use that information to parse on other sites for medical things (there's quite a few sites that take the data file as an upload, actually). I'd be interested in reading a more comprehensive audit though.
(I will admit to not having compared more than a handful of SNPs with what 23andMe has to say about them, and I suppose they could have tampered with the data, but that seems like a lot of effort for the one-time payment they got from me...)