I wouldn't recommend any books by Malcolm Gladwell. He oversimplified things for the sake of telling stories.
If you want to learn rigorously, better look toward academic sources.
Which academic sources would you recommend on this topic?
I've checked the sources from that book and they seem legit, including papers and articles[1]. Besides, the reviews of that book are very positive [2].
[1]: http://guides.skylinecollege.edu/c.php?g=279172&p=1861295 [2]: https://www.amazon.co.uk/Outliers-Story-Success-Malcolm-Glad...
My recommendation is to read the academic sources, not the guy who simplified materials to an extent that things are lost in the translation leading to misrepresentation and misunderstanding.
Also, always read the negative reviews. Sometime, they are bunk, but they sometime can be very informative.
I Strongly recommend this book: Outliers by Malcolm Gladwell.
He studies outliers, their family, culture, timing. One of many fun facts is that almost every pro-hockey player in Canada is born in the early's month jan, feb, mar.
Why? they compete versus small children when their are kids, and those months of strength give them advantage, which sent them into better teams, with better coaches and so on..