My Mom thinks that my Panic Disorder is not caused from my past traumatic experience because she has had traumatic experiences as well but does not have panic disorder, is it possible that different people react differently?

And that if two people underwent the same problem that one would possibly come out with a mental disorder and the other one be almost unaffected?

Also, this experience happened when I was young, my mom asked me why I never told anybody about it. I don’t know the answer to this, what would make a child not mention to their parents that they were being sexually abused? (Age 3).