Oracle, I believe that your son will make his choice by his own heart
Why do you assume that people choose their mates exclusively based on their hormones? (heart is just an organ, it doesn't affect the choice in any way)
How you feel about somebody is not affected just by the appearance of that person. You might be initially attracted to a person due to his or her physical appearance, but unless you are very shallow you will also base your feelings for this other person on the views, the culture of this person and many other attributes.
Personally I don't think I could have any positive feelings for somebody that supports crimes against my country and I wouldn't expect my children to do this either. If they did, then I would not be happy about it.
Beyond this, there is the question of language. I would want my grandchildren to speak Greek, and also not to be forced into any religion. Other that this I don't care what ethnicity the persons my children will choose will be.