Using resources to trace family is a popular hobby. This family tree is intended to help someone organise their ideas in the early stages of tracing their family. It can be a sensitive issue in this day and age (adoptions, step parents etc, as well as identity theft). It could also be applied to historical families.
It could lead to some rules about the number of ancestors in any given generation (eg 2 generations back from myself I would have 2 to the poer 2 relations; in the 5th generation 2 to the power 5)
It could also lead to paradox discussion (if we all have so many relations in past generations, why was the population smaller then?)