Anything North of 140 is rarefied air, but is not a predictor of success in life.
I'd be interested to know which test Rowan took as most standardized tests in the US are only accurate to 145 and in the UK to 140.
Then, there are the areas of cognitive ability that can also come into play. Examples are people who can memorize anything, but have trouble tying their shoes or feeding themselves. Others, who can't remember shite, but can solve complex algorithms in their head.
Bla-bla-bla...
Also... One test does not a Genius make. My scores have varied over the last 20 years from "modestly-high/not quite Mensa" up to "no, really, stop laughing". Cognition has always been a fascinating study...
The old SAT test (pre 94) would top out at about an estimated 168 IQ if you managed to scored 1600.