Where am I from?

This question has been playing on my mind quite a lot recently and I honestly don't know how to answer it. There is the obvious answer that I am from my mom and dad, that my body and genes are a mash up of there's which have created me - a randomly unique person, but my thinking goes deeper than that. Where does my anxiety come from? Why can I not deal with arguments? Why am I so sarcastic? Some of these traits can be ticked off by simply looking at my dad and his mom (my nan), put us in a room together and it is strikingly obvious just how similar we are. Then there are the genes from my mom, the way we both desperately want to please others often at our own expense, the need to be liked and the hidden shyness. I like that I am a blend of people, but recently I've hit a rock. My mom was adopted, and I've become somewhat conflicted about where I am from. My paternal grandfather was black - I can thank him for my dark hair, the skin-tone that can make people assume I am from anywhere in Europe and my ability to tan in an instance. I don't know who he is or what he looks like, same with my paternal grandmother and this is where my thinking begins. Is anxiety something I could trace back through them, I wonder if there was a history of eating disorders or an overwhelming desire to please others, of course I'll never know the answers to these questions and that for me right now leaves a gaping hole in my thoughts. I am beginning to understand exactly who I am, but I may never know the reasons why I am me.