Different cultures

I was reading about infertility and learned that in South Sudan, in the Nuer ethnic group, an infertile woman can be considered as a man and assigned to be the father of a child. I remember reading about another ethnicity in Africa where the family system is not based on marriage as we know it, but rather on polyandry and once the child is born, a father is chosen from the different men the mother knew. If we go back in time, we will notice that homosexuality was part of a normal Roman family where the head of the family tutors a young man and uses him as a dominated partner. Human race is so diverse that beliefs, rules, ethics, culture are so different in time and space. So from this point of view, I can't be shocked when I hear that the man who killed his aid in London and will probably be sentenced there for life in prison for murder, will get the death penalty elsewhere, for being gay , not for commiting murder.