The House of Athens

                             Erichthonius
                                   |
                               Pandion I
                         __________|_________
                         |         |        |
                     Erechtheus Philomela Procne___Tereus
    _____________________|______________________________
    |                |                |                |
 Cecrops Boreas___Orithyia Apollo___Creusa___Xuthus Procris___Cephalus
    |                                 |                    
Pandion II                           Ion             
    |
 Aegeus___Aethra
        |
     Theseus___Hippolyta(Antiope)___Phaedra
             |
         Hippolytus

cited from: Hamilton, Edith. Mythology. Little Brown & Company, January 1950.

Some gods appear more than once within the family trees up so far. This is because the family is quite large and the duplication is there for continuity.
Note that this tree has the least incest so far.
See:
The Genealogy of the Greek Gods and Goddesses of Mythology Metanode