Why is Libby fourteen?

This question arises regularly in book groups and someone asked it in a comment in Goodreads. I’ll go ahead and answer.

First, it’s not as if I had a choice. Child sex victimization happens to children. Thirteen/fourteen is the age at which children start to do more than cry under the bed. They’re old enough to do something. Libby can continue to put up with it at home, or strike out on her own. Which would you prefer?

Libby tries for more. Thankfully, she finds friends who help. Thankfully, she has good baseline skills of cooking and cleaning from her life on the farm. To the degree she succeeds, that simply goes to her credit. She was pushed into adulthood.