If this really was a big concern, you wouldn't be hearing all the complaints of airlines charging to ensure parents can sit even close to their kids.
To those who say "why risk it?"... It is simply a question of likelihood VS $$$... The chances are so small the airlines are quite happy to charge parents for the luxury of sitting with their little ones. I have 3 kids and they have flown all in one row many times. My wife and I prefer it.