Genetics is an ugly argument that is a little too close to Final Solution nonsense. The history of the world is one of movement and immigration. Constantine surely is Greek. Is there any word on him or are they just at their house all the time since he is older and having health issues?
I will also say that culture plays a big part in who you are and in no way or shape instead Constantine or the children Danish. Certainly their mother is but she clearly brought up her children aligned with her husbandís cultural background and it shows. They have Danish ancestry obviously but they arenít Danish.
Itís a bit like people calling Charles a German because he speaks German in Germany.