How would one answer the question "Are Poles fat"? It's all subjective opinion and the answer should be: "It depends - some of them are, some are not."
Yes, it depends, my dads family is from a rural farming area and my mums family is from a smaller town. Im sure you may find there is some common link between their heights and their environments.
it isn't a silly stereotype, silly stereotype is that all poles do is drink.