Maybe it's part cultural, part economic, part practicality .As children they might have an easier time finding string teachers in their community. It's an easy instrument to carry around and store in the home, especially if you live in an urban setting. It's also a prestige instrument and that might dictate their choice of instrument. And this is so un PC, but maybe they have a better natural ear for the instrument.
I've never thought of a violin as a prestige instrument. In my family we have a trumpet player and a French horn player and I've never thought to put instruments in a class. But now that I ponder on it, I would hold a brass or wind instrument in higher regard than a percussionist, even though to be good at any instrument, there is a huge amount of dedication required