Kif explains to the crew that his race reproduces through touch, their skin being a semi-permeable membrane which can absorb genetic material. They become sexually fertile whenever they experience strong positive emotions for another being, as Kif did with Amy on the HoloShed. Fry points out that everyone on the ship touched Kif while he was trying to hang onto them to prevent being sucked through the hole and it is unclear who the mother is. Professor Farnsworth uses an invention of his, the Maternifuge, to determine the real mother. The machine filters out its occupants based on a DNA sample, revealing that the mother is Leela. Amy is instead only the "smizmar" of Kif's children, which nevertheless makes her the "real" mother by Kif's standards. Amy is dismayed at being cast in the role of a mother, however, her parents are surprisingly happy about having a grandchild and demand Amy and Kiff call Amy's Mum "Grandma" all the time, however, at Fry and Bender's apartment for the pre-birth celebrations, Amy runs away.