When WikiLeaks released all of their data, almost nobody in the American voting population read it. Nearly everyone who did so was in the media, an intellectual, or a member of a political organization (governments, activists, terrorists, etc). Gene sequencing would likely be similar. The amount of data pulled out of a candidate's gene sequence would be so large that the only information about it the voting public got would be what the different political parties' ad campaigns wanted to get out there. Fox News would report every unfavorable feature they could find about democrats, MSNBC would do the same for republicans. The Mind Killer would be as strong as ever.
I don't think this would apply to genes greatly predisposing a candidate to being a sociopath. (The h+ article focuses on these kinds of genes.)
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.