There is a reason why random mistakes occur. The genes themselves carry a code for mutation which is expressed randomly without generational continuity. It may be considered recessive in the extreme. The ability for random mutation to "test out" new designs is at the very core of Darwinian evolution. These mistakes are supposed to happen. If they did not happen we would not be sharing this very info with each other as we would not exist.

We make mistakes when we are in a hurry.

There are no mistakes list to determine which are mistakes. To make sure no mistakes are committed consult a professional.

Everyone makes mistakes. Making mistakes is simply a part of being human.

They make you feel upset, but mistakes are mistakes.