Early on in her pregnancy, the first friend of my generation (X) who had a child commented that it was a weird process because it starts from apparently nothing and after nine months there's a person you have to look after. The fact that this was a wombate and ovariate (made-up words) person suggests to me that the perception that human reproduction is a peculiar process suggests to me that it isn't merely my male socialisation which makes me see it as odd. It could be said that the oddness is due to patriarchy - parasitic implantation of gametes is constructed as normal but the growth of offspring inside someone isn't because it rarely happens to men. It may be impossible to step outside one's cultural identity, so maybe that is the only reason it seems strange and we just can't see that it isn't, or it could be that it just doesn't seem so to most people.
Suppose, then, that this is strange:
Now consider this:
Here's another one:
Now imagine you're a child at a school next door to an artificial limb factory and you know nothing of the Facts Of Life. Occasionally you look out of the window and see realistic-looking arms and legs being loaded into the back of a van which then drives off into the distance. You surmise that there's probably another factory somewhere assembling the limbs with heads and torsos into complete human beings which parents-to-be then buy from a shop. Your belief that this is so is further reinforced by the fact that some of the shops you see on shopping trips with your parents contain inanimate people standing around in the windows. Presumably they are activated when the purchasers take them home. Again, however, you would probably be impressed by the oddness of the process.
There are all sorts of other possible ways in which people might hypothetically reproduce, and all of the ones I've mentioned so far seem quite bizarre. In fact it seems that almost any imaginable way people might arrive in the world seems weird. Babies hatching out of eggs is another one. Pregnancy slash birth is the process whereby we actually come into existence of course, and it does seem peculiar, at least to me and my uterus-owning friend, even though we both now have virtually grown up children and hang out with a load of regularly pregnant people. That doesn't stop it being bizarre, and the fact that it seems as much so to her as it does to me makes me think it can't all be to do with gender or biological sex, or even patriarchy. Of course, it is also the most natural thing in the world. Why does it seem so strange then?
The story of someone dividing into two and becoming a soldier and a Tai Chi instructor is "normal" in the respect that we generally find it in some respect ordinary when someone goes to a battlezone and comes back traumatised or injured, or perhaps neither of those things but definitely changed, but changed in such a way that isn't a startling break with the everyday scheme of things. A Tai Chi instructor, likewise, trains to carry out their craft and interacts peacefully with their students, and perhaps gains insights or practices which most people wouldn't, but again all of this forms a relatively seamless, smooth process. It's the thought that these two people were originally a single individual which is striking here.
The question therefore arises of whether there is any way at all in which new people might arrive in the world which wouldn't seem odd. I think there is, and it can be seen in the works of the philosopher Derek Parfit, but there's no need to look him up. Suppose people regularly lived thousands of years and stayed healthy. This is in itself not particularly peculiar, but rather like the assumption many people implicitly make about their lives when they're young and reckless. They consider themselves immortal and invulnerable. In this scenario, people's memories are not perfect and various traits about them may change gradually. They may become more or less aggressive, get better or worse at maths or learn a new language. As time passes, they may completely forget their early lives, and a monolingual English-speaking aggressive Caucasian maths lecturer called Derek may become a placid monolingual Japanese-speaking East Asian stay-at-home dad still called Derek but with no memory of his past at all. This person has nothing in his body which used to be there and no recollection whatsoever of the person he used to be. I would say there are at least two Dereks here.
This to me is not peculiar. It lacks the shocking oddity of the other examples, but is still in a sense an instance of a person coming into existence in a way which doesn't actually happen although similar things do happen to a lesser degree. In fact, many people do believe something like this happens in the notion of reincarnation - the identity of the person stays the same even when they haven't even got the same body. Whether or not reincarnation actually occurs, it is a very common idea which arises in cultures with no apparent connection to each other, so it's clearly something which sits very easily in the mind and is easily accepted by all sorts of people.
This example of humdrum emergence of new people is less startling than pregnancy and birth. It's rather boring in fact. This is because we are not equipped to deal with the ideas of people suddenly coming into existence almost from nowhere and suddenly ceasing to exist, even though births and deaths happen all the time. Most of us constantly strive to survive, so we're focussed on death, but there's an asymmetry because we don't fear our prior non-existence. Nevertheless we do regard coming to be as deeply hard to accept as a normal part of life, and in fact it isn't a normal part of life because it's its start. We don't have a problem with the idea of objects being manufactured or, say, a blob of lava cooling into a rock or ice forming in a freezer from the moisture in the air because we're used to the idea of non-living matter doing this. We do, however, have a problem with new people popping into being. This is because we cannot easily conceive, in the sense of emotional conviction, that people are just lumps of matter, and in fact if someone did we would find it disturbing. I would suggest that this is a healthy and straightforward way of seeing the world and the people in it which we may extend to other living things but which we can't healthily reject, and the fact that birth seems odd to me at least is what that's about.