I learned about the string theory today! If you take something, lets say a rock, and start making smaller and smaller pieces. You get a pebble and then sand and then even smaller pieces. When you can’t make it any smaller, that’s a molecule. Molecule is made of different kinds of atoms.
Atoms are made of of a nucleus and there are electrons going round and round that nucleus. Nucleus is made of proton and neutrons. Protons and and neutrons are made of little things called quarks.
So now there are different kinds of quarks and electrons and similar things. And it turns out that these quarks and electrons are actually strings. And depending on how the strings vibrates, it could be an electron or a quark or something else.

That explains why electron has to be in a certain way, because a string can’t vibrate in any old way, so that’s it. Nobody knows for sure, but it seems right to me.