This is from the same site, Baring the Aegis.
Genesia – The Genesia seems to have been a festival of the dead–especially of dead parents. It was celebrated on the fifth of the month of Boudromion in Athens, but that is all we know for sure. There is reason to believe that the Genesia was panhellenic–although we do not know if all city-states performed the rites on the same day. We are also unsure if the Genesia was a set day for all children to visit their parents’ grave and perform sacrifices there, or if there was a public commemoration of all parents. The day is also sacred to Gaea, who housed the remains of the dead, and brought fertility and wealth to the living.