Nobody knows. At this time the charge on an electron is a thing that we measure and put into the theory. There is not, at this time, any way to calculate the charge on an electron.
There was some tantalizing work done on the idea of magnetic monopoles, by Dirac.
https://en.wikipedia.org/wiki/Magnetic_monopole
The idea of magnetic monopoles is that the gauge field becomes, eventually, close enough to the actual monopole, something else. That something else is determined by the nature of physics at very high energies, and so very short distances. For example, if string theory is correct then the gauge field eventually shows its string-ness. And that let's you get a monopole.
But there is a mathematical theorem that is known in slang terms as the "hairy ball theorem." It is often quoted as "you can't comb a hedge-hog." It means that a vector field that is tangent to a sphere cannot be everywhere smooth. And that is a problem. In electromagnetism, the A field and the B field are perpendicular. So if the B field from a monopole is radial, then the A field has to be tangent to a sphere. And that is a problem. You get a place where the field is "weird."
Dirac's way around this was charge quantization. If the ratio of the magnetic field on the monopole and the electric charge on the electron was exactly the right amount (or integer multiples) then the "weird" place in the A field would not be observable. It would go away in the phase, which is not observable.
The problem is, so far, nobody has observed any monopoles.