There's an important quote very applicable to this:
If you attend only to favorable evidence, picking and choosing from your gathered data, then the more data you gather, the less you know.
I predict that the astonishing amount of objective evidence, both good and bad, that gene sequencing could provide will allow both sides, using the same data set, to build extremely formidable arguments for and against any candidate. The nature of the exposure of the information - by the candidate's enemies - makes this even scarier, as they will comfortably get away with exposing only the worst of any given data set. I don't suppose h+ would consider running a piece in opposition?
I wrote an article for h+ predicting that the rapid fall in the cost of gene sequencing will allow U.S. voters to learn much about presidential candidates' DNA. The candidates won't be able to stop this because:
DNA analysis has a decent chance of reducing political bias by providing objective information about candidates. If, for example, 70% of the variation in human intelligence is determined by identified genes then DNA analysis would reduce disagreements among informed voters over a candidate's intelligence.