If there's a ton of evidence for this, please provide some citations. I for one have never heard a single scientific claim for individual people having 20-30% N

If there's a ton of evidence for this, please provide some citations. I for one have never heard a single scientific claim for individual people having 20-30% Neanderthal DNA. As the sibling comment said, there may be that much Neanderthal DNA spread around in total, but no single individual sapiens has more than a tenth of that.