huh?
You are telling me if an unmarried woman in kenya has a baby...HER BROTHER ASSUMES FATHERHOOD? that is strange. Does he take the baby away from her?
He, of course, may also be an uncle and have children for whom he is responsible.
The whole point of serial polygamy is to prevent your family from being wiped out by a single disease. You end up with offspring all over the place ~ at the same time as a male you perform the duties of a father (as seen from the Western perspective).
I know of groups in America who do something similar because of a problem called "Indeterminate infertility". They will go through up to 5 spouses in the course of their lives just to make sure they have at least one child.
Bill Clinton's parents did that.