Are the tribes determined by the Father's lineage, or the Mother's?
Answer From The Annual Reading Schedule - Week 31 Notes For Numbers: The Father's. We always see tribes referred to as "their Fathers' tribes", such as in Numbers 1:16. Also, we see in Numbers 36:6 that the daughters of Tselophchad (Zelophehad) had to marry within their Father's tribe, not their Mother's tribe. Why? Because tribes were determined by Fathers, not Mothers. A woman automatically becomes part of whatever tribe she marries into. If her husband dies, and she remarries someone from a different tribe, she again changes to another tribe. Even Numbers 1:18 says, "they declared their ancestry by clans, by their Fathers' houses". It's very clear that lineage and ancestry is dictated by the Fathers, not the Mothers.