According to Melakuera, Emilia was "born from the same cursed blood as the Witch" as well as calling her "the descendant of the Witch".

Is Emilia the daughter of the witch?

Emilia. Certain people, such as Echidna and Pandora, have referred to Emilia as "the witch's daughter", with Pandora also mentioning that she was of the witch's bloodline after seeing her power, hinting at some sort of connection between the two, though nothing has been explained, yet.

Is Emilia really a witch?

Emilia is not the Witch of Envy as she was just a child when they sealed her. Furthermore, when Subaru told Emilia about 'Return by Death,' she died, which would not make sense if she was the Witch of Envy. ... As we all know by now, Satella and the Witch of Envy are different personas caused due to the Witch Factor.