How can you become mixed race?

Answer 1

A human that is of mixed race means the parents of the individual come from two different ethnic races or a mixture of races. A mixed race individual may also be referred to as bi-racial (coming from two races) or multi-racial (coming from more than two races).

Answer 2

If you want to become a human with mixed races (ethnicities), you can't. The race you are when you are born is the race you will be for the rest of your life, and that cannot be changed.