Presuming we're considering whether he's a genius in a musical context, he simply does not qualify. What makes someone a musical genius is the presence of a highly creative element - something nobody else thought of previously. Pushing the accepted boundaries via creativity and not just through angst and indifference to life. It's predicated on innovation. Cobain did not meet these criteria. He was competent at simple musical forms, but that's about it. He was lucky in that the world was ready for his style at that point - but that doesn't make him a genius. He was the typical angry guy who playing simple chords in basic patterns. It was cool to listen to but hardly different from punk music and had been done by 1000 bar bands before him. Nirvana was marketed well and his popularity and legend got a bump due to his early death. 'Genius' is a gross exagerration of his worth.