This portrayal of an Iowan farmer and his daughter (actually posed by Grant Wood's sister and his dentist) is surely among the world's most referenced art works, captivating viewers since Wood painted it in 1930. Ever since then, they've wrestled with the question – was Grant Wood satirising these serious, plain-living country folk or celebrating them? What is he saying about life in rural, post-war depression-era America? It’s not something that Wood ever answered outright. That ambiguity and those enigmatic stares have opened the (Gothic-style) door to a century’s worth of debate and a whole lot of parodies, with everyone from Kim Kardashian to Chewbacca to Amy Schumer to Donald Trump taking their place in this politically charged icon of a nation.