Outside an atomic nucleus, a neutron decays into a proton, an electron and an anti-neutrino within 15 minutes.
From this, we can conclude that a neutron is a proton with an electron stuck to it.
However, this does not explain the neutrino.
Free neutron decaying into a proton, electron and anti-neutrino
My initial thought on this was that the neutrino functioned as some kind of glue, but I have since come to a different conclusion.
From this, it follows that both electrons and protons are filled with neutrinos at above average pressure. Neutrinos are keeping electrons and protons inflated due to their tendency to stay inside fields of equally charged walls.
We can then imagine a free neutron as a proton with an electron stuck to it, and with neutrinos bouncing furiously inside of both the electron and the proton.
This can go on for some time without anything happening. However, at some point, one of the neutrinos inside the proton will make a direct hit at the electron. It will rip the electron loose from the relatively weak binding between the electron and proton.
Observed from the outside, we see the neutron spontaneously decay into a proton, an electron and an anti-neutrino.
In the physics laid out in my book, all flavors of neutrinos are merely differences in charge and energy, and not due to any fundamental difference. The anti-neutrino label is therefore nothing more significant than a reference to a specific energy and charge measured for the observed neutrino.