For the most part if you’re drinking anything made from corn in the US (all bourbon, some vodkas) you’re drinking genetically modified corn. Spirits from other crops too. In many (most? all?) export markets, however, you can’t use this. Thus many (all?) bourbons make a GMO-free version for export.
Because most of Four Roses bourbon is sold in Japan, however, their product is GMO-free, even in the US. However, distiller Jim Rutledge said he didn’t think there would be enough GMO-free corn left in a few years so things might change.
Now, does anything from the GMO crop pass through distillation? I don’t know; I’d guess probably not. But people may want to support non-GMO farming. It’s the same with organic booze – you probably can’t taste the difference, but you’re putting your support behind organic farming.