The tale I usually tell my myth students is that Helen was kidnapped as a baby by Theseus and returned fairly young as well. According to Pausanias, the Argives (and some poets) told a rather different story about her.
“Near the shrine of the Lords is the temple of Eilêthuia, set up by Helen when Theseus was passing through to the Thesprotians with Peirthoos after Aphidna was captured by the Dioskouri and Helen was being taken to Lakedaimon. Some say that she was pregnant and that she gave birth in Argos and then built the temple of Eilêthuia but that she gave the child she bore to Klytemnestra—for she was already married to Agamemnon—and that she married Menelaos after these events. The poets Euphorion of Khalkis and Alexandros of Pleurôn have written poems on this matter; before them still, Stesikhoros of Himeria also agrees with the Argives that Iphigenia was Theseus’ daughter.”
πλησίον δὲ τῶν ᾿Ανάκτων Εἰληθυίας ἐστὶν ἱερὸν ἀνάθημα ῾Ελένης, ὅτε σὺν Πειρίθῳ Θησέως ἀπελθόντος ἐς Θεσπρωτοὺς ῎Αφιδνά τε ὑπὸ Διοσκούρων ἑάλω καὶ ἤγετο ἐς Λακεδαίμονα ῾Ελένη. ἔχειν μὲν γὰρ αὐτὴν λέγουσιν ἐν γαστρί, τεκοῦσαν δὲ ἐν ῎Αργει καὶ τῆς Εἰληθυίας ἱδρυσαμένην τὸ ἱερὸν τὴν μὲν παῖδα ἣν ἔτεκε Κλυταιμνήστρᾳ δοῦναι—συνοικεῖν γὰρ ἤδη Κλυταιμνήστραν ᾿Αγαμέμνονι—, αὐτὴν δὲ ὕστερον τούτων Μενελάῳ γήμασθαι. καὶ ἐπὶ τῷδε Εὐφορίων Χαλκιδεὺς καὶ Πλευρώνιος ᾿Αλέξανδρος ἔπη ποιήσαντες, πρότερον δὲ ἔτι Στησίχορος ὁ ῾Ιμεραῖος, κατὰ ταὐτά φασιν ᾿Αργείοις Θησέως εἶναι θυγατέρα ᾿Ιφιγένειαν.
Here’s a fragment from Euphorion (fr. 90)
“Because, in fact, Helen gave birth to her with Theseus who violated her with force”
Οὕνεκα δή μιν
ἶφι βιησαμένῳ ῾Ελένη ὑπεγείνατο Θησεῖ.
There is wordplay here with Iphigenia and iphi-biêsamenô.