Measures of pain have been reported for many population groups. Researchers often try to include patients with a variety of backgrounds. African-American, American Indian, Alaskan Native, and Hispanic are just a few of the groups used by the U.S. Census. Social researchers tend to use these same groupings.
In the last 25 years it's become clear that pain is not just a biologic or medical experience. Emotional, cultural, and social factors are equally if not more important. The passion with which your aunties express their pain may be more behavioral than physical. It may or may not be based on their ethnic background.
Some psychologists look for pain with an emotional overlay. This means patients who have pain respond to it in a different way because of their emotional or psychologic make-up. They tend to describe their pain using phrases like "it's killing me" or "the pain is torturing me". Other emotionally based words might be "frightening," "vicious," or "miserable".
Whether or not there is a physical or biologic reason for pain doesn't matter to the person's experience. Everyone of any ethnicity feels the pain just as if it were very real.