The only contemporary source which refers to Sappho's life is her own body of poetry, and scholars are skeptical of biographical readings of it. Later biographical traditions, from which all more detailed accounts derive, have also been cast into doubt.
An Oxyrhynchus papyrus from around AD 200 and the Suda agree that Sappho had a mother called Cleïs and a daughter by the same name. Two preserved fragments of Sappho's poetry refer to a Cleïs. In fragment 98, Sappho addresses Cleïs, saying that she has no way of obtaining a decorated headband for her. Fragment 132 reads in full: "I have a beautiful child who looks like golden flowers, my darling Cleis, for whom I would not (take) all Lydia or lovely..." These fragments have often been interpreted as referring to Sappho's daughter or as confirming that Sappho had a daughter with this name. But even if a biographic reading of the verses is accepted, this is not certain. Cleïs is referred to in fragment 132 with the Greek word pais, which can as easily indicate a slave or any young person as an offspring. It is possible that these verses or others like them were misunderstood by ancient writers, leading to the biographical tradition which has come down to us.
Fragment 102 has its speaker address a "sweet mother", sometimes taken as an indication that Sappho began to write poetry while her mother was still alive. The name of Sappho's father is widely given as Scamandronymus, he is not referred to in any of the surviving fragments. In his Heroides, Ovid has Sappho lament that, "Six birthdays of mine had passed when the bones of my parent, gathered from the pyre, drank before their time my tears." Ovid may have based this on a poem by Sappho no longer extant.
Sappho was reported to have three brothers; Erigyius (or Eurygius), Larichus and Charaxus. The Oxyrhynchus papyrus says that Charaxus was the eldest but that Sappho was more fond of the young Larichus. According to Athenaeus, Sappho often praised Larichus for pouring wine in the town hall of Mytilene, an office held by boys of the best families. This indication that Sappho was born into an aristocratic family is consistent with the sometimes rarefied environments which her verses record.
A story given by Herodotus and later by Strabo, Athenaeus, Ovid and the Suda, tells of a relation between Charaxus and the Egyptian courtesan Rhodopis. Herodotus, the oldest source of the story, reports that Charaxus ransomed Rhodopis for a large sum and that after he returned to Mitylene, Sappho scolded him in verse. Strabo, writing some 400 years later, adds that Charaxus was trading with Lesbian wine and that Sappho called Rhodopis Doricha. Athenaeus, another 200 years later, calls the courtesan Doricha and maintains that Herodotus had her confused with Rhodopis, another woman altogether. He also cites an epigram by Posidippus (3rd c. BC) which refers to Doricha and Sappho. Based on this story, scholars have speculated that references to a Doricha may have been found in Sappho's poems. None of the extant fragments have this name in full but fragments 7 and 15 are often restored to include it. Joel Lidov has criticized this restoration, arguing that the Doricha story is not helpful in restoring any fragment by Sappho and that its origins lie in the work of Cratinus or another of Herodotus' comic contemporaries.
The Suda is alone in claiming that Sappho was married to a "very wealthy man called Cercylas, who traded from Andros" and that he was Cleïs' father. This tradition may have been invented by the comic poets as a witticism, as the name of the purported husband means "prick from the Isle of Man."