What kind of research is conducted in the lab (storywise, I mean, gameplaywise I know the answer)? Maybe Darin could claim he or Bailey came into contact with a substance that caused the blue pigmentation during pragnancy? Depending on how hard-science Vs. fiction your setting is they might even get a compensation from the lab owners/government.
But even so homeschooling would be the best option to not draw attention.
(On a sidenote when a similar problem occured in a spinoff of the Elfquest comic series, the protagonists claimed it was "body paint" and "very hip". Later background characters spread that lie and although it was never explicetely mentioned, I imagine that started a trend, lol.)
