Sounds like a classic case for using subforms, providing I understand your question.
In the related tables (the "child records"), they would each have their own
primary key, and they would each have a "foreign key" (which is the primary key from the parent table). I am assuming this is what you want, so that multiple Interests can be added relating to a single volunteer, for example.
IntKey VolKey Interest
1 1 Programming
2 1 Bowling
3 2 Programming
4 3 Cooking
4 3 Soccer