What does it mean when someone says their Puerto Rican from birth & Mexican in the heart?

Some people mythologize other cultures and feel like if they just pander enough they can become that thing. We see this a lot in the US where suburban white kids buy a few rap songs and suddenly start talking like Lil' Wayne. But Puerto Rican island culture bears almost no similarity to Mexican culture except perhaps in the dominant language and religion. So whomever is saying this is just kind of a poser.

It means they're brown

It means they consider themselves Mexican or love and relate with the Mexican culture even though they're not Mexican. Probably because they grew up in Mexico or a neighborhood with a high concentration of Mexicans or they have a lot of friends that are Mexicans, etc.

They spend more time in Mexico than in Puerto Rico.

it nneans they like nnexican people too

It means they Puerto Rican from birth & Mexican in the heart