Many to Many DAO

I have a question about many to many relation with DAO design.

I have an object User with a userDAO and an object Interest, with InterestDAO.

I have a many to many relationship between both, a user can have many interest and an interest can have many user.

My question is : Do I need to create a third object and a third DAO to do the junction table ? Or do I create a Collection of person in Interest, and a list of Interest in person ?

Thanks !