Thoughts on Mixed Race and Identity

My roommate is 1/4 black which he highly values and to a large extent identifies as.  That being said he is physically white with complimenting blond hair and blue eyes.  He is incredibly smart and has huge amounts of knowledge on civil rights and the struggle of black people thought America, but has a poor social filter leading to some awkward comments in public.  He occasionally makes seterical comments about being a black slave, and while technically his black heritage makes it more socially acceptable to make comments such as these his appearance causes heads to turn and comments to be made.  I know that he is making a joke or a commentary on something, but it always makes me feel uncomfortable.  It is this that got me thinking about how I and America define race and identity, especially when physical appearances don't match up with race or identity.  I do believe that people should be able to identify themselves how they wish whether it be gender or racial, but I'm not convinced, or at least apprehensive about anyone defining themselves as anything.

Being mixed race has never been easy in this country where respectability and privilege is so closely linked with race.  Due to this rigid social and institutional structure have been set up to define race and identity.  Mixed individuals have always had a harder time finding acceptance within racial and social groups due to their mixed blood.  Despite this the globalization of the world will only cause the world to become more and more blended and it will become harder and harder to categorize people based on appearance.  So the question comes back to how we define ourselves and how the social norms allow us to define ourselves.  I'm under the impression that people are able to define there gender and sexuality, but I don't think that racial identity is as fluid as gender.  I would not say that a white man with no black ancestor can define himself as black.  However, I have know clue at what percent blood I would deem it acceptable to proclaim yourself as something, but neither do I believe that there should be some science or mathematical formula to determine these things.  So i'm stuck relying on my gut , which can be equally unreliable.  I want to be open minded and accepting, but at what point to we delude something to the point of meaning nothing?  While a world with no racial categorization sounds nice, I also feel we would lose a piece of our culture and humanity if we were to forgo all things.  At this point I'm just rambling but I want to reiterate some of my big questions I hope the comment sections could respond too.

How do you define race and identity?

Are gender and racial fluidity equivalent?

At what point do you think someone can identify themselves as part of a different race?

How much does physical appearance play into racial identity?