Genetics with more breast tissue?

To preface I want to speak very respectfully and not come across as stereotyping. My whole life I have had auxiliary breast tissue no matter what weight I have been. I am on the leaner side. Through my research I have noticed that south Asian women almost always tend to have auxiliary breast tissue like myself, I actually am a quarter south Asian. When I observe other women of different backgrounds they do not have auxiliary breast tissue to the same extent. Has anyone else noticed this?