Ben Smith provides some of the context behind the conspiracy claims from the suspects’ parents and aunt:

The Tsarnaevs may sound like the craziest figures of the American fringe. But they come by their paranoia honestly: Russia’s cynical and brutal governments have, for centuries, murdered their citizens in general, and their Chechen citizens and subjects in particular, under any number of pretexts. … And you don’t have to be crazy to believe Chechen allegations of baroque and brutal government conspiracies — at least, not when they’re directed at the Russian government.

… “They are ascribing to America things that are familiar to them at home,” [former Washington Post reporter David] Satter told BuzzFeed Friday, of the sort of incident that fringe lunatics in the United States claim as “false flag” attacks, and that Russians call “provocations.” “It’s not surprising that people have reacted that way,” he said.