no your donor must not have the same percent ethnical background, no worries. When down to the level of genes, the ethnical background is no longer something you need to worry about.
In general the match should be as compatible as possible, but as long as a SCT is not something you need to worry about right now, there is no need to find a matching donor.
In case you are interested, I can provide some links / information regarding SCT - can't do that right now, as I'm a bit in a rush.
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