What makes someone Jewish?

In Jewish History class my teacher continuously asks us "what makes someone Jewish?". I truly do not know. Some people answer "knowing prayers" or "having a Jewish parent" or even "if someone says they are Jewish that makes them Jewish".

I am Jewish. I say that I am Jewish. I have two Jewish parents. I know prayers. I am Jewish. But what makes me Jewish?

I was enrolled from a young age at a Jewish Day School where half my day was dedicated to studying the Tanach, Taffilah, and Rabbinics. Even with those hours of focused learning, I do not know what makes someone Jewish.

I have grown up in a Jewish household. In my family we celebrate main holidays, all of my siblings and I had a bar/bat mitzvahs, and mezuzahs placed on each door, but how do those things contribute to someone being Jewish?

This question comes in my head a lot because I am living with over 60 Jewish kids. We all have one thing in common; we are Jewish. How does that connect us? What is connecting us?