Why do USA born people with Mexican parents call themselves Mexican?

Sometimes is a matter of racism.

Let say " you were born in U.S.A.from Mexican parents, obviously you "looks" Mexican.

You are nor black ,nor white, neither Chinese.

Then , "You Are Mexican "

Then the Mexican kid early in the school will say "Gabachos de mlerda ,I am Mexican! !!"

Porque está es en la constitución mexicana. Son mexicanos los que nacen dentro del territorio mexicano y los que nacen en el extranjero siempre y cuando sus padres hayan nacido en México. Obviamente, la mayoría de gente en México no los considera mexicanos pero ante las leyes de ahí si son mexicanos. I really hope you have understood me.

Its their heritage and personal preference.

THEY SHOULD BE CALLING THEMSELVES FAT SMELLY WET BACKS

yes

I am irish, as in irish american.my friend is a mexican, as in mexican american.

Nobody is really American so

Because the rule is, unless you're Asian, the minority part of you is your race. That's why the first colored woman to attend Harvard is Elizabeth Warren, because she's 1/32 Cherokee and 31/32 white. That means her great great great grandpa was Cherokee, so of COURSE that would make her Cherokee!

They are nationalist

Because that's their ethnicity. Lmao, that's like saying a black guy in an all white school is white. No, because he's black?