How to Change History with Sex

So let’s say you have a time machine. You don’t have one and you never will, but let’s say you do. I’d like to convince you that using it is extremely dangerous to your existence, and that of everyone you’ve ever known. Because history is a lot more delicate than you think.

It really doesn’t take much effort to disrupt the past. If you want to remove Hitler from history (as so many do), you don’t need to lend Von Stauffenberg a hand at the Wolf’s Lair in 1944, nor do you need to correct Hitler’s itinerary in Munich in 1938, when he narrowly avoided Johann Georg Elser’s bomb. You don’t need to become any one of his would be assassins (a list that’s already suspiciously long).


Instead, you need to know one thing: the time and place that he was conceived. For Adolf Hitler, this is sometime early in August 1888, in an Austrian town called Branau am Inn. At some point in those weeks, Alois and Klara Hitler found some private time and made an embryo that would one day be responsible for the deaths of millions.

Yet long before any of those millions of people heard the name of Hitler, millions more were denied the chance to exist.


The ejaculate of the human male contains hundreds of millions of sperm. From the moment they enter the vagina, they’re in a race to see who will reach the egg first. Most of them die before they even get that far, because the vagina is too acidic for them to last long. A few hundred struggle through, but only one will deliver a package of 23 chromosomes to be matched with the 23 chromosomes of the egg, and create the blueprint for a new human being – just one out of hundreds of millions that could have been created.

All we need do to kill Hitler before he’s born is to make sure the sperm that represents him is replaced by another one. How do you do this?

Knock on the door of Alois and Klara’s bedroom at the right moment.

This will annoy the hell out of them. You should probably run away before they come to the door. But if you can get them to do that, then you’ve won. Because the choice of which sperm fertilises the egg is random enough that the slightest change in events surrounding the conception will result in the creation of another human being entirely. Plus, there’s a nearly 50% chance that the new child will be female, which will most likely put her out of the running to become a fascist dictator.

(sure, a woman could get the job now, but not in early 20th century Germany…)

And so you return home to the 21st Century, secure in the knowledge that the lives of millions have been saved. And what do you find?

Every single person you ever knew is gone. So are their parents. And in many cases, so are their grandparents. But then you think: okay, well, that isn’t surprise. Events have changed, and people have been swept around a bit. Maybe your parents moved to a different town. Maybe whole populations are in different places.

But no. It’s worse than that. They’re gone. They never existed. They were never born. They’ve not even been replaced with people who look like their brothers and sisters. The whole world has a completely different population, all because you stood outside a door in 1888 and yelled loudly. Why?

Well, it’s pretty simple. And you should have realised. Or did you think that one rejigged act of conception would be the end of it? Remember, all it takes is a tiny change in the timing of the sexual act, and a different child is born. And once you have a different person in the world who takes different actions, then other moments of conception begin to happen differently.


It could start immediately. Perhaps Alois Hitler is so annoyed by being interrupted in the act of love that he’s irritable at the customs office the next day. His short temper winds up everyone in the office, and one of the men there moans about it to his wife later on. This annoys her, and she decides to shut him up by dragging him to bed, leading to the conception of their next child several hours earlier than originally scheduled. Thus a different sperm fertilises the egg and a different child is born.

And it’s not just about sperm, either. The egg that emerges from the ovary every month or so isn’t predetermined, and changes in life situation or hormonal balance could well influence the choice. As time goes by, the female contribution to the embryo will change just as much as that of the male.

And so it goes on, with the changes growing greater and greater once the new Hitler child is born and starts to have a more active influence upon the world. What if little Adolf cried loudly, but his replacement doesn’t? This could have a profound effect on any conceptions that might happen with earshot.


It builds up much faster than you’d expect. People that Adolf met and influenced in his life will lead slightly different lives because of his absence. They may end up living in different places and marrying different people; this would certainly happen to August Kubizek, who only moved to Vienna and pursued his musical career at Adolf’s insistence. His children would end up being completely different people, born at different times in a different town, meeting different people and having different children.

The ripples of change spread outward from Branau am Inn as the years pass, and by the time you reach the First World War, it’s likely that a significant percentage of the armed forces of both Austria and Germany aren’t the same people. It’s possible that many of the future Nazi leaders will also be gone, if they were born later than Hitler. Goering, for example, was born in 1893 in a Bavarian town not a million miles away from the Austrian border – close enough to be affected by all the tiny changes.

(it’s impossible to say whether the first world war would still happen. It probably would, given that the people in charge were born well before 1888, although it may start in a different way – especially if the life of Gavrilo Princip (b. 1894) is affected)

So by the time people of Hitler’s generation are reaching an age where they can start to have an influence on politics, the cast of players is fundamentally different. Would the Nazi Party have arisen? Quite possibly. But they wouldn’t have had the oratorical talent of Hitler to wrench them out of obscurity. The underlying course of history in the 20s and 30s might have remained broadly the same, but the people who could change the course of history would be increasingly different – and thus history would change. By the 1940s, the vast majority of people in our world were being influenced by the megalomania of Adolf Hitler, if only in the sense that it disrupted their lives and thus affected the timing of the next generation’s conception. Without him, there would either be no Second World War, or it would have been profoundly different.

And thus the world you know would cease to be. And so would you.

Your parents wouldn’t meet and produce you, because they never existed. Your grandparents might, if they were born early enough and managed not to be affected by all the changes emanating from Austria; but a lot of them would be gone too. Different children are born, grow up, meet different people, form different families, and give rise to a world of strangers.

blank family tree

Even if you knocked on a different door in a different town back in 1888, you would still end up with a changed world in which many, if not all of the people you know are gone. The course of history might be closer to what we know now, but there’s no escaping the change in population. It would still spread outwards from the initial instance to the entire globe, given enough time.

The act of conception is one that is so utterly delicate and random that any change will have the profoundest effect upon history. All it takes is the slightest change of time and place, and a different human being is created – erasing the original descendants from history and replacing them with another set of people.

So when someone invents time travel and decides to go back in time to eliminate Hitler, stop them at once. They may save millions of lives. But they will destroy billions of others. Including yours. Even if all they do is go back and knock on a door…