The most eldest---and therefore most authoritative---record is the epic poem Theogony by Hesiod (circa late 8th century BCE)---whose name can be affectedly, but poetically, pronounced He-side.
Other classical writers supplement and often contradict Theogony---Greek mythology was an evolving collage originating from various sources with NO strict canon.
See Wikipedia: Family tree of the Greek gods for some of what Hesiod and others winged up.
Poetic license commanded that yours truly engraft historical persons who are mythic---with mythic geneologies.
Vertical and oblique solid lines indicate parent and child; horizontal solid lines indicate parents.
Dashed lines indicate descent, but NOT parent and child.
The time increases roughly going down, but compaction required some out-of-sequence orderings. Also many of the mythological persons have no fixed origin date, just the mythic past.
There are some anomalies in the entries to be described below.
His/Her/It's name does NOT mean "chaos" in the modern sense, but gap, gulf, chasm, or void. The later makes most sense for a creatio ex nihilo.
The Proto-Indo-Europeans flourished in the 4th millennium BCE, and so Zeus may be the oldest Greek god in the historical record.
Psyche is the only person without a mythic geneology.
Credit/Permission: © David Jeffery,
2016 / Own work.
Image link: Itself.
Local file: local link: theogony.html.
File: Ancient Astronomy file: theogony.html.