In Mexico speaking a foreign/European language has prestige. So, in most mixed Russian/Mexican families I know children (including by now grown-up children) do speak passable Russian. This Russian tends to be a lot better if either only one parent (usually the mother) speaks it, or if both parents are Russian. However, there are some families where the Mexican spouse can, actually, speak Russian as well (if, say, a guy studied in Russia and came back with a Russian wife) - and I have noticed that the children then have a much heavier accent in their Russian: they unconsciously copy their dads.
I know this is a little off-topic, but I'm curious: How large is the Russian community in Mexico? I remember finding it unusual when I found out you were a Russian living in Mexico. I wouldn't think that there'd be very many of those.