Without a will how would assets be divided?

A couple of years ago when my uncle died I was told his deceased siblings children received equal shares as his living siblings. I always thought that was incorrect. I always thought his deceased siblings children should have shared their parents portion. My father is aging and refuses to make a will. He married our mother twice. I was born in between marriages and he does not appear on my birth certificate but he has always acknowledge me as his child, even had health insurance from him as a child. He had four children, one died as a baby, so we have 3 remaining children. We all have children. My brother recently passed away. I believe when Dad passes my sister will get 1/3, I will get 1/3 and my brothers grandchildren will receive 1/3 divided between them. I live in CA, Dad and sis live in MI. I need Mi law for this. Am I correct on this?