What makes a Celtic supporter?

Everyone on this forum is a Celtic supporter. It's an important part of who we are. And I wonder if there are common characteristics in our backgrounds that contribute to us being Celtic minded. For example, if you were born in Glasgow and have an Irish name and your Da was a Celtic supporter, then the chances are Celtic will form a big part of your life.

Of course, Celtic is open to everyone and times have changed, and we all have different reasons for loving the things we love. But I wonder if there are other similarities, such as if we generally come from working class or poor backgrounds, or if our politics are of the left, or if, in our own small way, we have a strong disposition towards making the world a better place for those who are disadvantaged. We're not considered to be the world's best supporters just because Celtic is such a wonderful club. It's because of the type of people Celtic supporters are. So, when you meet someone, is there anything about them that makes you think this person would or wouldn't be a Celtic supporter? What is it about them that makes you think, yes or no?