请问这个句子有问题吗？

colorfulUID: 16619

有没有出错？其中的两个破折号，什么是“of-and”
Gut men argues convincingly that the stability of the Black family encouraged the transmission of-and so was crucial in sustaining -the Black heritage of foldlore, music, and religious expression from one generation to another, a heritage that slaves were continually fashioning out of their African and American experiences.
谢啦

sailing_yfUID: 150982

个人认为句子的结构如下
and so was crucial in sustaining 是和encouraged the transmission of并列做动词的。两个－只是连字符，起分割和迷惑的作用。最后一句的a heritage 是和from one generation to another有关系的（具体说不出来），一个名词加以解释that slaves were continually fashioning out of their African and American experiences.
请多指教

luckannUID: 154637

i think the short sentence "so was crucial in sustaining" is a interpolation here.it modify "the stability of black familiy",mainly on :the stability.just in my opinion:)