"[Leo Quintum: Is that...?] A map of Superman's genetic code. I reverse-engineered it from his 24-hour super serum. I also finally figured out how to replicate it. [Leo Quintum: No...] Of course, it will require an ovum from a healthy human woman."
January 1, 1970
https://en.wikiquote.org/wiki/Last_words_in_Superman_media