I'm
guessing the case is this, vesta dear:
nadin has a brother who's a physician, and lives in Ohio (or he might be an uncle).
nadin has a sister who's a dietician, and apparently lives in the United States.
nadin's mother is pretty ancient, and has lived all of her life in Mexico (or damned near all of it); she's used to it, and as with many elderly people, resistant to trying something new.
nadin grew up among the 1% of Mexico, meaning her mother has the means to travel to this country any time she wishes (for medical care and all that).