Everybody who's responded to you so far has a pretty good point,
>>1, and it's good to get all of the varying perspectives that you do. I'll go ahead and throw in my two cents as well.
I'm mixed ethnicity; to be succinct, I'm half latino and half Western European; to be even more blunt, part brown and part white XD. Now, I love my mixed heritage because I can trace my origin to a bunch of places, you know? From Panama to Germany to, perhaps, Africa even; I honestly don't see anything wrong with that. I don't see anything wrong with being genetically homogeneous either. That's because I think race conflict is absolutely inane and stupid and, though it really doesn't need to be said, judging somebody off their superficial appearance is a pet peeve of mine and I think it's incredibly stupid. I understand your plight; you feel torn apart and half-baked because of your heterogeneous ethnicity. I see where you'd feel uncomfortable and it's annoying to have people judge you that way.
But it doesn't really matter, to me anyways? Why?
Ignorant people have permeated humanity for, well...forever. There will always be stupid people to give you grief for nothing; racist people are no exception. The very concept of racism is hypocritical, unfounded and stupid but it still exists because there are hypocritical baseless idiots in the world anyways. Sometimes they're just raised that way, and in that sense it might not be COMPLETELY their fault, but it's still a character fault one ought to correct. What you look like and your blood can be completely tangential or even unrelated to who you are. Using your racial schema as a way to define your place in the world is incredibly limiting. I personally have never done that; I don't associate with black or white or asian or latino people, I associate with human and human and human and human people. That's how it should be. Next time you come to a place where you interact with large sects of your family, you know, try keeping that in mind and approach them as people with potential interests in something you want to talk about, and at that point if you still don't feel like you can connect, well, that happens since people are different. That being said, don't deny your culture either; just acknowledge where you come from and appreciate it, but leave it at that and live as you rather than trying to live vicariously through your heritage. This'll also help you comprehend where other people are coming from without offending them or being affronted by how they receive you, in that you'll be able to identify cultural influences without being bound to them. In this sense, you can liberate yourself from the shackles that bind you and actually elevate your ability to integrate amicably with others. Humanity transcends our skin, and people worth talking to know that.
Of course you deserve to belong. But what do you want to belong to? Basing your societal home group on ethnicity is common, and I respect the decision to do that, but diving into your own "faction" to the point where others are seen as outsiders or opposition is in my mind a good way to turn superficial differences between people into a quasi-ideological war over what is essentially nothing. I don't belong to one ethnicity or another; I belong to my myself, I fit in with my family and friends and my beliefs give me my place where I stand. It can be that simple, if you push yourself into thinking in such a way, and, while you can't change the bigotry and ignorance pre-existing in others, you can at least try to mitigate the spread of mindless hate and misunderstanding, and nullify any bearing it has on your enjoyment of life and the company of others whatsoever.