All human beings have ethnicity and all human beings demonstrate in-group behaviour, that is culture.
That cultural behaviour is not inherant and instinctual but is learned. I have lived in another country that had different cultural practices to my native culture and I observed my adoptive country's behavioural norms willingly as they did not conflict with my own values and were concordant with them. The conflict we see in Europe from mass immigration is the enforced migration/immigration of people whose culture is very different from their adoptive country and with a strict, rigid belief system such as Islam prescribing and proscribing the behaviour of men and women, there is a clash where the cultural norms are not compatible. Many are fleeing war or fleeing poverty and their survival drive sends them to Europe, yet they are culturally conflicted in many cases and have a hard time adjusting and integrating. My own opinion is, if you do not approve of or feel comfortable with the culture of a country you have migrated to, you should move to a country that suits your culture. When in Rome do as Rome does.

I see that as often depending on where a family or individual is raised, and lives.

No

Have you ever met a firey woman who could celebrate Quanza and St. Patrick's Day? Then you would understand.

Well being a cultural Jew is ethnic as well-ask Hitler.