> What you mean by that?
I was thinking about a celebrated quotation by A.N.Whitehead: "The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato."
> it does not mean that we are defined by what his mentor supported
Plato's entire written corpus consists in Socrates speaking. If you accept Plato's great influence, you have that.
Supposedly. We have no idea to what degree Plato's character of Socrates resembles the real one. It's a pretty common strategy even today to put one's own ideas into the mouths of famous dead people, as that makes them seem more profound.
What you mean by that?
> We are defined by being Sparta supporters.
Even if you assume that "Plato went on to start the whole "Western civilization" thing." then it does not mean that we are defined by what his mentor supported.