It’s fair enough if you want to believe that America is the home of giants because the majority of a small number of people competing in a relatively small league happen to be from America. Despite what you may think there are mad tall people competing in all sports around the world, the majority, obviously due to the size of the world population, not being American. Yes, there are not many sports where height is as much of an advantage as basketball, meaning that there is a high percentage concentrated in a small area. So, these tall people are selected and trained to be basketball players based upon their genetic attributes using the immense sporting infrastructure surrounding basketball, which simpy doesn’t exist elsewhere, despite the game being popular. Perhaps it would be more interesting if you try to provide the rationale behind why you think America has more really tall people? The NBA isn’t an answer btw. Is it something in the water?