shahmaran, I wouldn't have a problem with your "nativity" approach if I didn't know that you want to use it to excuse things like ethnic cleansing with "logic" like "Hey, the came to Cyprus 'just' 3500 years ago. That means it is OK to refuse to them their human and democratic rights, ethnically cleanse them and replace them with Turks". This is truly a Hitler like mentality.
Also I disagree with you about the genetics part. Here we are not talking about the human kind, which evolved in Africa more than 200.000 years ago and spread all over the world. Here we are talking about ethnic groups. The ethnic groups which exist today were created in the last 5000 years or so. What is common in ethnic groups is things like language, religion, culture and a common identity, not necessarily the DNA. They don't make you a DNA test to determine to which ethnic group you belong. The DNA differences between people are minuscule and they do not determine the culture, language, religion or anything else related with ethnicity.