Half-blood is an expression that means just what you describe, a person whose parents were of different ethnic origins.
It is considered offensive (in the US anyway). If you watch old American westerns, you will hear the term used in reference to people of mixed Native American and European parentage, almost always disparagingly.
This is such a sensitive topic in the US that many people shy away from any reference to ethnicity, sometimes to an absurd degree. However, some possible expressions are mixed race, mixed heritage, Thai-Chinese (ancestry), Asian (heritage), and so on.
Americans are so gun-shy on this topic that you could call yourself just about anything and no one would question you. In the U.S. I would avoid expressions that use the word 'blood', though. They remind Americans of the vile laws stating that 'one drop of black blood' made a person black (and therefore not eligible for full status).
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