To add to other excellent comments refuting this line of reasoning - brains are not rocks, they are very complex systems, and the more complex something gets the more delicate it is, i.e. even a tiny chance has a chance to alter behavior of the system in significant ways.
As an illustration, think of your computer. If you open it up and remove one RAM die, it will most likely run fine, albeit slower. Were you to introduce a "tiny difference", say, swap two pins on a die, you risk getting everything from machine not booting up, to crashing constantly, to running fine but spewing out nonsense and corrupting data every now and then. Were you to introduce a little bigger change - say, saw the die in half, you'll likely fry the whole machine.
As an illustration, think of your computer. If you open it up and remove one RAM die, it will most likely run fine, albeit slower. Were you to introduce a "tiny difference", say, swap two pins on a die, you risk getting everything from machine not booting up, to crashing constantly, to running fine but spewing out nonsense and corrupting data every now and then. Were you to introduce a little bigger change - say, saw the die in half, you'll likely fry the whole machine.