She wasn’t born with it, but a certain medical condition made her like that. I always wondered how it felt for her to experience her hearing ability decrease everyday.
In a nutshell, life is simply how you look at it. Mary looked at the bright side of it and made it to her advantage. People learnt to live with her and some wished they were like her. It doesn't matter how incomplete you are, how you live will choose to eliminate it. My teacher once told me," life is a choice, not a chance".