Jane's conception was unconventional, to say the least. Theresa had drugged and kidnapped Heather, Ethan and Gwen's surrogate, so that she could be implanted with Gwen and Ethan's egg. Her plan was to withhold the child unless they gave her back Little Ethan, whom the courts had taken away from her. When Theresa experienced some spotting, she was convinced she had miscarried, so she drugged a drunken Ethan and, dressed as Gwen (including Gwen's nightgown, Gwen's perfume and a blond wig), raped him (only Theresa, Pilar and Whitney know it was rape, as Theresa has not revealed the truth about slipping him the date rape drug -- Ethan and Gwen are fairly certain, but have no proof). When she learned she was carrying twins, Pilar pointed out that that one or both could belong to Gwen, but Theresa planned to keep them no matter what. The doctors determined that Theresa could not possibly carry both twins to term, but rather than do a DNA test and abort whichever child was not hers (which was what Theresa had wanted to do), Ethan convinced her to let the doctors decide by letting the stronger baby live.
When the baby was finally born prematurely, the hospital would not allow Gwen to see her until she produced the papers terminating Theresa's parental rights. Unfortunately, just as she was obtaining those papers, Theresa announced that the child could be hers. A DNA test proved that the baby belonged to Theresa and Ethan, and the assumption is that the boy belonged to Ethan and Gwen. Theresa took the child home, but when Jane developed a fever and took the baby to the hospital, Gwen took off with her. While Theresa and Ethan search for their daughter, Gwen is in hiding with the baby, whom she has renamed Ashley, on the Crane compound along with Katherine. Although Katherine has reminded Gwen that Theresa is the biological mother, Gwen has reminded Katherine that Theresa signed away her legal rights and that Ashley is her daughter now.
Ethan, Fox and Theresa eventually made their way to the Crane compound, where Theresa and Gwen came face to face over the baby and had a violent confrontation which left the others wondering if Theresa had killed Gwen. After Ethan made it clear to both women that he was staying with his wife, they promised the feud was over, and Ethan promised Theresa that as long as she didn't press charges against Gwen, he wouldn't take the baby away from her. Shortly after getting back to Harmony, though, Theresa called Sam to have him arrest Gwen, determined to get Gwen out of the way so that she could have Ethan to herself. Her plans backfired when Ethan called her out as a monster, and even though Theresa tried to use the baby to get him to stay with her, he stuck by his promise to Gwen. The courts awarded temporary custody of Jane to Gwen and Ethan, and after Theresa's visitation was terminated by the courts, it seemed as though custody became permanent as Gwen and Ethan no longer needed permission from Theresa to do anything, including take Jane out of the country if they wished.