Je ne connais aucun autre homme aussi têtu. D'autant (plus/moins) qu'il n'était pas question de n'importe qui, mais de sa propre sœur.
Firstly, in the sentence above, which of these three expressions is really fit for use -- and why? When the preceding sentence has a negative construction such as "ne... aucun", is it necessary to use "d'autant moins que"?
Secondly, I’m not fully sure how these expressions differ in meaning from simply using "parce que".