The Silence Sunday Family

Agnes Tachyon was in her laboratory as usual when out of nowhere she did a DNA test with her saliva and that of her colleague Manhattan Café; what was supposed to be a simple experiment ended up turning strange
Agnes T: That's strange... The tests show that...
look at coffee
Are we sisters?
Café spits out his coffee and looks at Agnes
Manhattan C: That... is impossible...
Agnes looks at her monitor and notices that she has relatives with Agnes and other UMAs.
Manhattan C: We have relatives with... Special Week, Fuji Kiseki, Silence Suzuka, and others?...
After reading their names, Manhattan Café decides to call her friends and colleagues
Manhattan C: sending text "Come to Agnes's lab... we have something important"
After 15 minutes, Special Week, Fuji Kiseki, Silence Suzuka, Agnes Tachyon, Air Shakur, Neo Universe, and Marvelous Sunday appear.
Special Week: What happened Café-San?
Fuji Kiseki: Did something happen, Cafe?
Air Shakur: I hope this doesn't interrupt my data collection session
Marvelous Sunday stares at the monitor screen and notices someone else on that list... The mother of their eldest child was "Sugar Heart," a female umamusume, but none of them had heard anything about her. All that is known is that she had a human child and that Sunday Silence abandoned them as soon as she found out he would be human.
The more they investigate, the less information comes out... and that's when they decide to get to the bottom of the mystery.