Both the passage and the lecture discuss about the development of lactose intolerant. The passage claims that lactose intolerant results from people not regularly consuming dairy foods. However, the lecture disagrees. The lecture says that lactose intolerant is genetically inherited from parents.

First, the passage says that lactose intolerant occurs in cultures that do not consumes dairy foods occasionally. The passage brings up an example of Chinese, who had never drank milk in ancient times and had hard time consuming dairy products in present. On the other hand, the lecturer refutes about this. She says that lactose intolerant often occurs in cultures that regularly consumed milk. The lecturer supports this by giving an example about Indian. She states that although Indian population drinks a considerable amount of milk, about half of the population remains lactose intolerant.

Second, the passage claims that lactose intolerant also occurs in people who do not have dairy foods in their regular diet. The passage gives an example about Japanese. It says that about eighty percent of the population is found lactose intolerant, since they do not eat dairy products after infancy. Again, the lecture disagrees. The lecture states that lactose intolerant can develop as people age. The passage says condition develop in many cultures, not just the cultures that do not regularly consume dairy. The lecture supports this by bringing up an example of Mexican population, who loses ability to digest dairy products as they become older.