This is precisely what I was thinking. Something interesting that I hadn't thought of before is that we now actually live in a time where genome sequencing has become cheap enough that low-N studies (like those in MRI/fMRI-based studies) can actually begin to participant-match based on genetic background. This might become the new gold standard!
Sequencing might become cheap enough to do that, but our understanding of the functions of the different genes is so lacking that I don't think a lot of meaningful data can be extracted for most studies' subjects.
I don't think we necessarily need to know the function of the genes in order to create a participant matching paradigm that is better than what is being employed currently. For example we can get a more precise snapshot of ancestry using sequencing than simply relying on self-reported 'race'. Also I don't think it needs to be a perfect match; simply stating that controls matched case participants within X percent ancestry would be a useful statistic to report in the methods.
