@pmrsuzie

“Are genes or is the environment to blame?”

The million dollar question.

I used to teach to my students that mutation is a force of nature. It is a built in survival requirement. Most of the time it has negative consequences. But, sometimes, rarely, it is beneficial to the species and promotes survival. That is its purpose. And, the species survives.

I know it is hard to view PMR as anything but negative, physically.
Mentally, it certainly fosters humility. And for some, there may be a final positive physical result.

Best wishes.