I’m under the impression that those countries are more convenient for the company, either having locations or it being more convenient to arrange pay or something, based on the inclusion of American rather than an ethnic background.
Edit also it says nationality rather than Heritage, so it’s pointing to what country you have citizenship with.
A lot of choices are made for us. People who think it’s down to only choices probably ignore all the luck and privileges they experienced. I could have been born in much worse circumstances than I was, and that would not have been due to any choice I made. Children dying in war zones made no choices to get there.