I have no idea why northern cultures worshipped murderous sky gods. I only know that they did, and that they eventually over-ran the rest of the world. Patriarchal dominance hierarchies spread because they were disruptive, not because it was a good social system. Agriculture is the traditional demarcation line between egalitarian cultures and dominance hierarchy based ones, but it isn't quite that simple. There were proto-agricultural enclaves and early cities that were still egalitarian for many thousands of years.

I'm currently reading The Dawn of Everything, which sheds a lot of light onto this topic. I hope to write something about it very soon.