People like him, are made by many, many random acts, and of course dedication, around 10.000 hours is need it for be an expert in any field, any. What if "grandfather who was a grocer" was a plumber instead?

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..