  The absence of magnetic white dwarfs with a non-degenerate low-mass stellar
companion in a wide binary is still very intriguing and at odds with the
hypothesis that magnetic white dwarfs are the progenies of the magnetically
peculiar Ap/Bp stars. On the other hand, we cannot resort to a process that
impedes the generation of a strong magnetic field in the main or pre-main
sequence progenitors of white dwarfs if they are in a multiple stellar system,
because such a process would also prevent the formation of magnetic cataclysmic
variables consisting of a magnetic white dwarf accreting mass from a low-mass
companion. This is the reason why it has been proposed that fields in white
dwarfs may be linked to their binarity and are generated through a dynamo
mechanism during common envelope evolution.
