and on the other they know that the fear is groundless Are you sure about this? I know many people who have irrational fears, who use any statistic they can get their hands on to “prove” how grounded their fear is. Or, they ignore all statistics and justify their fear based on whatever they can find, sometimes using anecdotes. Furthermore, I don’t believe that the example of flying in an airplane is a good one for examining how similar or dissimilar our personalities may be. With regards to heights, it is easy to explain why many humans are apprehensive about them – it’s a survival instinct. The human body doesn’t have much of a chance to survive a long fall. Natural selection may favour a human who was apprehensive around heights over one who may not be apprehensive, as the non-apprehensive one may have higher odds of dying due to a height-related fall (considering that for most of human evolution, we did not have reliable tools to aid us with heights). Another angle to consider is the speed at which our bodies move while in a plane. Such speeds are not speeds that human bodies are built to travel at. Our instinct for survival recognizes this, and thus may cause us to become apprehensive. Flight is still very new to us, when you consider humanity’s entire existence. It’s no surprise that we haven’t completely abolished all fears related to it. Another thing to consider is the interesting fact that we are essentially old-world humans in a new-world era. Our brains have not evolved anywhere near as fast as our technology and sciences have. Despite our knowledge and awareness of who we are and how the body works, humans still have a ‘gut instinct’ that can lead them to a different choice or conclusion despite the abundance of evidence which shows the correct answer. For further reading on this, I highly recommend the book “Risk: The science and politics of fear” by Dan Gardner.