Do some research and pick an ancestor to model, build the model, and show how you are related.

For instance, you can build the tank your father was on in WWII. Then show the relation. It is as easy as "This was my fathers tank." This is a really easy example since a lot of us have parents who were in the military.

You can do a figure of Lady Godiva riding through the town square, then show how you are related, she is my 30th g Grandmother. (She actually IS my 30 gGrandmother)

Or do a 1946 Pontiac. This was my granddad's favorite car.

Maybe a figure of Uncle Ed when he was in the 101st AA.

Did you have ancestors on the Mayflower? Build it.

It would be open to all types of models. The goal here is to make something to honor your ancestors. Most people wont need to go any further than their parents or grandparents to find something interesting. The research is up to you and how much you want to put into it.

Maybe you could even do yourself?
http://s182.photobucket.com/albums/x309/CaptainA_photo/?action=view¤t=Model082.jpg