I read the same story from NY Times, which had a more detailed write up. She likely inherited the genes from her dad. "Likely" because they can't test her dad's genes since he's deceased. Her dad didn't really feel pain either, so growing up it was not that abnormal.
Her son has a similar mutation but daughter doesn't.
NY Times Article: https://www.nytimes.com/2019/03/28/health/woman-pain-anxiety...