Kirby: Does your DNA have you looking over your shoulder?

It could be you — you know, one of those people who are sweating the genealogical DNA fishing trips police are using to close out cold cases?The number of people who think they literally got away with murder long ago is dwindling. You might be parked in a nursing home somewhere and — voila — the cops come calling with a murder warrant.Police send decades-old DNA samples to genealogical labs, where they’re compared to millions of people who voluntarily surrendered their ge