An 15-year-old sci-fi short story I read on a creative writing website. It only featured female characters, though the author was male. It was set in an era where people could casually own vacation homes, workplaces, and research space stations in outer space, much like building a villa, office, or lab on Earth. A family of researchers was continuing their work on their own private space station. Only the mother, the head of the family, remained on Earth, while all the daughters were in space. From the eldest to the fourth daughter, they were all engaged in the same research and, despite their different personalities, got along well. However, as the research progressed, they found themselves short-handed. Not wanting to let outsiders in, the daughters asked their mother for a new sister. The mother immediately coordinated DNA, gave her growth promoters, and created and sent an infant. However, perhaps due to a DNA abnormality, the sisters were shocked when they saw this young fifth sister. It was obvious at a glance that something resembling a tumor was protruding from her body. The second daughter proposed surgical removal, but the eldest rejected it on the grounds of inadequate facilities. They decided to monitor the situation using anti-cancer drugs and growth promoters that would rapidly grow only normal cells.
Growing about ten years' worth in a few months, the fifth daughter was raised as a scholar through gifted education. Because of her illness, the third and fourth daughters felt sorry for her and raised her with special affection. However, for some reason, the second daughter didn't like the fifth sister and treated her coldly. Whenever the sisters quarreled, the eldest would mediate, spending her days complaining about the frustration to her mother via communication. The fifth daughter's chest didn't develop at all, which was surprising, but she grew very tall. Furthermore, one day, she attacked the third daughter with tremendous physical strength. The second daughter finally shot and killed the beast-like creature, which was excitedly holding high the tumor-like part by some means, and the other sisters had no choice but to accept it. According to the mother, the DNA used this time belonged to an ancient, extinct species called "men." The eldest daughter was appalled by the mother's research results and wished she had made a sister using only the DNA of their mother and grandmother instead.
Just to be safe, I'll write this again: the author was a male. It wasn't a piece of misandry written from a female perspective, but rather an unsettling story told from a male perspective. But perhaps because some idiots mistook it for the former and brigaded the site, it disappeared a few months later.