When I went looking for that exact thing a couple years ago, my journey started with 'The Man Who Mistook His Wife for a Hat'. It wasn't a science textbook on intelligence, but it fundamentally changed how I thought about the brain's architecture. Sacks’ case studies illustrate how specific cognitive modules can be hyper-developed or completely absent, which is more revealing about 'genius' than a dry IQ score. Then I found books like 'Thinking, Fast and Slow' by Kahneman. That one dismantles the idea of a single, rational genius, showing how even brilliant minds rely on heuristics and are prone to systematic errors.
I think the most satisfying reads connect the neuroscience to the lived experience. 'The Emperor of All Maladies' isn't about intelligence per se, but its portrait of relentless, obsessive curiosity in the fight against cancer is a profound study of applied genius. For a direct hit, 'The Neuroscience of Intelligence' by Richard Haier is dense but worth the effort. It gets into the gray matter, glucose metabolism, and the 'parieto-frontal integration theory.' It confirmed for me that while biology sets a range, the expression is all about the wiring formed by intense, sustained practice—the grind behind the spark.