Are you sure it is ethnicity and not that you are not part of the family? I think that being a family business there are norms at home that make their way into the business. There are conversations outside of work that influence work interactions which you will never get the full story on. That could be why she seems clickish. She probably has no idea if she hasn't worked much in any other environment. I don't have too much advice for you. You may have to "fake it" because they are probably completely oblivious to their behavior. This of your own family and how strangers might misinterpret except this is work and home.

I worked in a couple of family owned business and found you really had to 'earn' your way in. I was not really successful at either one. At work I also tend to not reveal much... it's just my style. Not being an open book in the second position this is exactly what got me into trouble.

My weird story... There was an office move at one point. Everyone helped load the truck and that was fine. Then it never occurred to me that I was supposed to go to the new office a few hours later an help after hours. On top of that there was this cisco installation which my boss expected me to know to sit and watch despite the fact that the room was this tiny closet with no air and there is no reason I need to know that information in that job or any other job before or since. This was all supposed to come to me via osmosis. I wasn't alone either. Another person didn't know either and took his girlfriend to the airport. The girlfriend was leaving forever so this was basically the last goodbye. They talked about him and then gave him a hard time when he got there after they called him. I really have no idea how he was supposed to know because they even made comments behind his back that he should have know. And I have no idea how they could not have understood he had other priorities in his life. Then we were all supposed to hang around and drink wine and have pasta like some sort of extended family. It was bizarro.