I know that on the first sight the question may seem dumb, as it's obvious that those born in Argentina will be better claycourters than those born in Australia and those born in GB will be better grass players than those born in Spain.
But my question is rather focused on two nations:
If you take a closer look at these two nations, it appears that many Austrians are left-handed, while many Croats are big-servers.
Muster, Melzer, Koubek, Bammer, Knowle
Ivanisevic, Ljubicic, Ancic, Cilic etc....
Why is it so ?
Probably Argentinians have much more claycourts, than courts with other surfeces. And they beginn to practise on clay in very young age. They have very talented players.
Being lefthanded or righthanded depends on dominant hemisphere of the brain: dominant left hemisphere = righthanded, dominant right hemisphere= lefthanded.