There is great tendency always to 'compartmentalise' this sort of thing and say "It ia just X" or "Just Y" rather like the pundits on the topic of what controls airspeed and RofD and as with everything it is nearly always a combination of effects.
I appreciate the OP asked for 'simple', so faster wing is the best, but yes, there are several factors, and no-one has yet mentioned roll due to fin sideslip yet
(and to get really technical, there is the small roll moment generated by rudder displacement alone...) An a/c with anhedral WILL experience a rolling moment in yaw due to differential wing speeds but it may well be masked by other effects.