A childhood belief about creepy crawlies

I grew up in an old farmhouse with old windows. We were always squishing bugs. Sometimes, my Mom would sometimes just flush them down the drain without squishing them, a practice that I was always very leery about. I was sure (and am still not entirely UNSURE) that all we were doing was contributing to the creation of a super-race of bugs that would be much more resilient to our squishing and flushing practices.