The eminent archaeologist Digger Dugan made the discovery of a lifetime when he excavated the ancient Greek city of Sparthens. There he found amazing evidence that the Spharthenians had a mythology considerably different from the one we're familiar with. His discovery was an ancient temple containing a row of twelve golden thrones, one for each of the twelve most important gods and goddesses in the Sparthenian pantheon. The Sparthenian mythology was obviously derived from that of the rest of ancient Greece, for the seven gods (Apollo, Ares, Dionysus, Hephaestus, Hermes, Poseidon, and Zeus) and five goddesses (Aphrodite, Artemis, Athena, Demeter, and Hera) bore familiar names, and their spheres of influence were familiar too. The males were the messenger god and the gods of fire, harvest, the hunt, light, the sea, and wine; the females were the goddesses of love, marriage, the sky, war, and wisdom; but the gods and goddesses didn't necessarily have the same sphere of influence, and parents (if any) of the god or goddess who sat there in the Sparthenian pantheon? Note: Left and right in this puzzle are from the point of view of someone facing the thrones, not of the gods and goddesses sitting in them.
There were two generations of immortals represented in the throne room. Four of the immortals were of the older generation; all four were children of Cronus and Rhea.
The other eight were of the younger generation. Of these, one had no parents, as she was born from the foam of the sea; another was born from the head of Zeus and so had a father but no mother.
The remaining six were born more or less in the usual fashion. All six were children of Zeus, but not all six had the same mother. Each was the child either of Zeus's wife (who was one of the goddesses in the throne room) or of one of three mortal women: Leto, Maia, and Semele.
The two centermost thrones belonged to Zeus and his wife, in one order or the other; on the other side of Zeus sat a brother of his.
There was exactly one pair of twins among the twelve immortals; they occupied adjacent thrones, but on the opposite side of Zeus from the god of light.
The goddess of war and Poseidon's mother were both members of the older generation.
The god of fire wasn't Zeus.
The god of the harvest didn't sit immediately to the right of Hera.
The eight members of the younger generation of immortals, in order of their thrones from left to right, were:
the messenger god (whose mother wasn't Zeus's wife), the god of wine, the goddess born from the foam of the sea (who wasn't the goddess of marriage),
an unmarried son of Zeus and his wife, the goddess with only one parent, a twin who was Maia's son, the goddess of wisdom, and Hermes.
Aphrodite, who sat just three thrones from Athena, wasn't goddess of marriage or of love.
The god of the hunt, whose mother was Leto, sat at one end of the row of thrones.
Demeter, who was the goddess of the sky and a daughter of Cronus and Rhea, sat somewhere to the right of the goddess of war.
One of the gods of the younger generation (who wasn't named Hephaestus) was husband of Athena; he had the same father and mother as Poseidon.
Dionysus and Apollo were from different generations; the younger of the two was the god of the harvest.
The goddess of marriage didn't sit next to Dionysus.