Patriarchy arose as a social system for the first time 5k years ago. It didn't exist in the Stone Age. There were no nuclear families 100,000 years ago - everyone lived together in a tribe that supported and cared for all of its members. If humans haven't changed since then, why do we now live in male-oriented dominance hierarchies today? 20k years ago there was no way to know who the father of a child was, so clan went through the mother's line. Besides, everyone took care of everyone else, so it hardly mattered who the father was - until about 5k years ago when you've now got agriculture, and more personal property and a highly stratified socials system for the first time ever and women's movements are now tightly controlled for the first time so as to be able to verify parentage.