katsuragi Akane never said much about the person who got her pregnant. The only led Lucien has about his father is from the kyuketsuki which stated they looked alike.
However, Shinji was able to get something:
"'She' was obsessed with research. 'She' liked conducting experiments. I remember one time when I was pregnant 'she' would take my blood, saying he needed more information on the baby."
From this Shinji could agree with Lucien that this person was a piece of trash who took Akane as a lab rat. However, that isn't the point.
At first, Reverend Jazz thought Lucien had two mothers. After all, 15 percent of the relationships are in LGBTQ+ community, and with the help of Tama, women can get each other pregnant —not men. However, Shinji has the keywords: 'uncle,' and 'father.'
No woman in the right mind would like to be called 'Father' by their daughter, and 'Uncle' by their niece, right? —even if it's a mad researcher.
