>>281318627
She wanted to fuck her brother, it's that simple. Sora is more or less a sockpuppet for people who want to fuck their siblings or cousins (Incestual desires are way more common in Japan, their religion is literally built on god fucking his sister and creating their land) but can't because it's stigmatized when the western norm is that incest is a big no-no, and Japan has been sucking up to the west post WW2. It's not just Yosuga no Sora, plenty of Japan mediums have incest fantasies but can't act on them because for fear of being ousted in modern society.