Handedness and Heredity

So I was talking to my mom today about how I’m less scared about birth than I am about difficulty breastfeeding.  This led to my all time most feared parenting challenge is having a left-handed child (please note tongue-in-cheek being employed I’m quite sure there are much more challenging things!).  I am SO right handed that I can’t believe how ambidextrous my sister has to be as a lefty.  I think it would actually be difficult to teach a lefty how to write or hold a pencil.  So, I decided to see if there was research on how heredity effects handedness.  It seems there isn’t a specific gene and it is variable but in general the overall balance of 90% right-handed vs. 10% left handed is constant across the world and generations.  DH and I are both right-handed and according to several studies our chances of having a lefty is about 9%.