Lets talk about teeth, as i'm English i have bad teeth (natch) and indeed lost my fourth on Monday. Considering the state my teeth were in in my late teens thats actually something of a miracle. However this sorry state of dental affairs could be largely down to a decision i made in my mid-teens.
At around 15 and with already poor teeth i was checked by a dentist visiting the school and given a letter to give to my parents telling them i should go to the dentist. Unfortunately the trauma of my previous dental visits (when i was 7 or 8) were still with me and i threw the letter away. Hence my teeth were allowed to get worse until an abyss finally forced me to go to the dentist when i was at university. Then i found that the horrors of fillings actually were not so bad because my mouth was a bit bigger than when i was 8...
But one simple decision so many years ago has probably caused me over 25 years of trouble (and a fair bit of cost too). It could be that if i had gone to the dentist as a teenager i wouldn't have lost the teeth that i have and my mouth would be in rather better shape. We'll never know of course.
But that is something i found interesting. Often people talk about major decisions and events that can have dramatic effects on the future course of history but minor decisions can have significant ramifications too. I remember at college i arranged to meet a fellow student at the weekend, unfortunately there was a mix-up and we didn't meet. I was pretty annoyed but decided to give him a second chance. A quarter of a century later he's still my best friend who i speak to every day.
Its because of how small decisions, forks and changes can have dramatic changes that the genre of "what if history" is entertaining but highly problematic. In some ways i think predicting the effect of small changes on a history time line is more difficult than major changes.