Does everyone have gallstones

I was wondering if everyone has gallstones.
Even if you have never had a problem with your gallbladder.
Which i haven't.
Also is it possible not to pass any stones with the flush, or i guess that will happen if the flush is not done correctly.
These may seem like lame questions, but i would really like to know.
My son and i are planning to do the flush together.
This should be fun we only have one bathroom.

I guess i better get the bucket out!!!