The following is a family tree (of sorts) showing the ancestry of the great heroes from each side of the Trojan War, beginning with the Titan, Atlas. It follows Roman conventions on naming. The word 'married' is used whenever a couple are joined by the birth of a child. This may not necessarily be accurate, but I have followed this convention for the sake of convenience.
Atlas married Pleione.
She bore: Tantalus and Oenomaus (who married Sterope). From these are descended the House of Atreus.
She also bore: Jupiter who married Maia, Electra who married another Jupiter, and Teucer. The latter two were the ancestors of the Trojans.
Tantalus had a child named Pelops, who married Hippodamia, the child of Oenomaus and Sterope.
Maia bore Mercury, who married Carmenta to Jupiter. Electra bore Iasius and Dardanus to the other Jupiter. Dardanus married Bateia, Teucer's daughter.
Atreus was born to Hippodamia and Pelops. He has two sons, Agamemnon and Menelaus. The former married Clytemnestra (what a mouthful) and had Orestes. The latter married Helen and had Hermione.
Evander was born to Mercury, and he had a daughter, Pallas.
Erichthonius was born to Dardanus, and he had a son, Tros.
Tros had three sons, Ilus, Assaracus and Ganymede.
Ilus had a son, Laomedon, who had Priam and Hesione.
Assaracus had Capys, the father of Anchises, to whom Aeneas was borne by Venus.
Hesione married Telamon and had Teucer the Greek. Aeacus, who appeared from nowhere, seemingly, had Peleus who had Achilles for a son. Achilles had Pyrrhus for a son.
Priam married Hecuba and she gave birth to the house of Troy: Hector, Ilione, Paris, Delphobus, Polites, Helen of Troy, who married Menelaus, Polydorus, Troilus, Cassandra and Creusa, who married Aeneas to have Ascanius.
It must have been comforting to those Romans who managed to decipher their family tree to know that they were descended from the gods.
Author's note: this family tree is by no means complete, and could do with an ASCII art version. I wasn't feeling confident enough to attempt that, but if anyone manages to do it, I'd be happy to see it here. In the meantime, The House of Troy and The Royal House of Thebes and Atreus are good family trees showing basically the same people, but without showing how closely related they all are.