I have no personal experience with European Dormice, so I cannot be much help, but I do know that several species really are ill-natured little beasts with sharp teeth, territorial obsessions, and no toleration to speak of. I assume that some family members do not want any rivalry and are dealing with hopeful upstarts in the most logical way open to them.

On the wetlands where I live the red-knobbed coots have similar habits, not only with their own chicks, but with any other water birds they find. Only a minority of their own chicks survive long enough for the parents to chase them off their territory.

Not sympatico birds at all! And I believe the dormice are not a lot better.