Are we talking 'metaphorical' father and son relationships here, as in the nodes in a graph that may be described as 'parents' and 'children', or do you really mean a list of fathers and their sons? (and not their grandsons as well?)

Essentially, the answer depends on whether the data you are modelling conforms to the rules of a hierarchy (i.e. it has a single root node, every child must have a parent, and the graph is directed), or whether you are just describing a general graph where nodes can be connected to each other, but without any further constraints.

Options that spring to mind are:

- A father table and a son table, joined on keys.

- Father and son records stored in the same table, using adjacency lists to reference between them (similar to how employee tables typically structure employee/manager relationships)

- The hierarchyid datatype

Without further information though, it's hard to recommend which is most suitable for your situation.