It depends on what kind of incidents or the degrees of seriousness.If someone got killed in a road accident then I don't think it would stop people from using cars,but it could influence the driver who was involved in that accident though.he will never forget what he had done and will drive much more carefully.
Another example is:although people learnt that war is bad and babaric but for centuries,countries were still at war with each other,In another hand,the war between China and Japan,had left with our Chinese people an forgetable scar.it can never be forgotten easily.
So,do incidents from the past continue to influence the present?The answer is yes and no!