Souths slavs are very slavic genetically, contrary to what some balkan nationalists want to say. Take a ukrainian and mix him with a greek and you get a serb. Thats still very slavic and also why south slavs are quite good looking.

Im only around 60% proto-slavic. I will never be a full blooded slav ethnically. I only care about being Slovak, being slav is just a nice second.