You are the 9% (if both parents are righties, then there is a 9% chance of a left handed baby).

What's interesting about left handedness is that even if both parents are lefties, the kid's chance is only 26%. Which is strangely low for something where there is some generic link.

If one parent is a lefty the chance drops to 19%, and if no parent is a lefty then it is 9%. The average over society is 10% of the population.

I almost don't wonder if generics isn't the primary reason that people are left handed, but generics can make you more likely to be a lefty (for whatever reason). That would somewhat explain the statistics.