I hate to carp on one element of this, but being smart isn't entirely the same thing as being a genius (though the people who sell IQ tests would like you to think it is true). Genius is about creativity and innovation. Being smart is about, well, being smart. The two are often related but it isn't absolute. Thomas Edison is often invoked in this regard. A smart man and a genius, but hardly a John Stuart Mill.

The other is handwaving at an IQ number is just that. It is meaningless outside the context of a well known IQ test (such as the Stanford-Benet and the Terman) and without knowing what the mean of the test is and the standard deviation you really don't know anything.

Finally, genius or not, you can goof up. I recall a meeting of the Philomathean Society of the University of Pennsylvania, open to the public. I attended. There were three Nobel Prize winners there: Gerald Edelman, James Watson, of DNA fame, and Baruch Blumberg. It was supposed to be a "nature versus nurture" debate. Professor Edelman took it seriously, but Jim Watson did not. You could tell he had too much to drink. He was slurring his words. He was very clever and his jokes were good, but the science he could invoke off the cuff wasn't of the caliber of Edelman's (who showed up with impressive color slides). To which I'd say: being a genius isn't an excuse for not being prepared.