As a mother I believe it is my sworn duty to expand the horizons of my children, so on a recent trip to Mexico I was determined that we would not have one of those “resort vacations” where the extent of the culture is contained in the fact that the staff is Mexican. Besides, I’d been to Mexico lots of times, so it was with no small amount of swagger that I announced to my daughters, 12 and 16, that we were going to ride the city bus to the market one day for lunch. They w