These are two of the first shoujo manga released in English, both are compilations with at least one story by Moto Hagio (A, A' is entirely by her, whereas in Four Shoujo Stories only one is, but it's by far the best one). I really can't recommend these enough if you're looking for some historical context on the shoujo genre, or break away from the vapid cliches that riddle most of the genre today.
The island of Ilegenes has made huge technological advances in the fields of cybernetics and genetic modification, earning it the nickname the "Genetic Sodom" for veering so far off the path of nature. These technologies are easily available to the wealthy through the thriving black market, which not even the government has the power to oppose - a fact that the young Fon Fortinbras Littenber is made keenly aware of after his parents are murdered for expressing anti-cloning sentiments. Now, the boy attends an elite military university, where he plans to work his way up through the system in order to re-structure the corrupt government and destroy the black market. But despite his hatred of cloning and human modifications, his impossible eye color and aptitude at academics and sports lead the other students to suspect that he is actually a modified human...
These are two sci-fi manga that, while technically being shoujo, will probably appeal more to non-shoujo fans than to shoujo ones. Neither of the manga have most of the annoying facets of the genre- cheesy drama, stupid high-schoolers, chibi humor, and a shallow plot. Really, the only way you can tell they're shoujo is the pretty artwork and stronger focus on emotions.
Both are partially about cloning and its moral/emotional ramifications.
More short, emotionally-charged science fiction by shoujo master Moto Hagio. Art is exquisite, plot finely crafted, and characters sympathetic, as is expected in her works. Fans of her sci-fi/outer space stories should definitely check these two out.