As far as the Bible is concerned, you are either a Jew or a Gentile.  Gentiles have no particular identifying characteristics other than that they aren’t Jews.  And Jews are a people who would have vanished if they hadn’t held on to their heritage to distinguish themselves.  They have to know that they are a Jew before they identify that way.  When they were told they were told that they were Jewish. So...they are a Jew.  

You can’t look at someone and know they are a Jew.  You can identify a Negro, Caucasian, or an Asian because they have certain physical characteristics.  But Jews?  They have simply held in their hearts who they are for over two thousand years.  And they choose to say they are Jewish...accepting the bias, discrimination and the accusations that they killed Jesus.

Current Jews didn’t kill Jesus, just like current Caucasians didn’t approve or own slaves--they are the descendants of those who killed Jesus, and Caucasians are descendants of those who did own slaves.  We need a do over.  Jesus said to love the Lord your God with all your heart and your neighbor as yourself.  It might be a good time to do that.  We are who we are now, not who someone used to be.  We need to just love each other.