One of the experiments aboard the International Space Station was genetically engineered mighty mice. A research team led by Dr. Se-Jin of the Jackson Laboratory in Connecticut sent 40 young female black mice to the space station in December, launching aboard a SpaceX rocket. Some of the mice were injected with a "mighty mouse" formula that involved blocking a pair of proteins that typically limit muscle mass. Bulked-up, mutant "mighty mice" held onto their muscle during a month long stay at the International Space Station, returning to Earth with ripped bodybuilder physiques, scientist reported Monday.
Source: The Greene County Daily World of 8 September 2020.
I suspect that the goal of this project was to help astronauts to maintain their muscle mass during long space flights such as a trip to Mars. But I suspect that some athletes might decide to go genetic leading to more scandals for the Olympics.