Perhaps it is different in your culture where respect to elders plays a bigger part than in the West (or so I understand).

Perhaps you can write a list of all the annoying things he is likely to say? Written down they may be more dealable - you might say in response to 'Once, he asked what I would do after I graduated the college' you want to help people and protect the environment and ask his advice on what might be jobs that meet this need. I think he will get the message.