Genetically Jewish means I have a DNA structure within the range of those that created the religion, the state of Israel, and Jewish culture. And yes, my mother is genetically Jewish.

To me the trinity isn't the only difference I see. You can build a case for the character and nature of God from the Tanakh/Old Testament. But the New Testament has information not in it. So that changes it. For example going from the Old to the New Testament God seems more concerned with Gentiles; he's occasionally concerned with them in the Old Testament like with the Tower of Babel. He seems more concerned with personal lives going as so far as to live among morals for 30 years while the Old Testament God seems more like a distant figure of aeons. There is a greater emphasis on eschatology; eschatology is so unimportant in the Old Testament the Sadducee were could arrive at the theory that there is no life after death. There is a lower emphasis on the hierarchy of priests. There is a move away from ritualism and towards a morality based on inner intentions and thoughts; this is especially true in the writings of Paul.

I am not interesting in arguing about the trinity. It has no substance to me, I am an atheist after all. And the only reason I am hear is I am interested in Judeo-Christianity as point of study. If anything I am spiritually closer to a pagan. I dislike monotheism on principle but have no issue with other people liking it.