There are two primitive tribes in a primeval forest. The totem worship of the two tribes is different. Tribe A worships snakes and thinks snakes are their ancestors. Tribe B worships birds and thinks birds are their ancestors. The totem worship of people in these two tribes is completely the same as that of their tribe. If the tribes are intermarried, the children born belong to this tribe. If the tribes are intermarried, The children born belong to the mother's tribe,
The statement "Someone's mother is from tribe A" must be wrong if someone is known to worship birds.