Red Cockroaches (2003)

At the train station, at a grave-site, a bored young man keeps running into a mysterious woman with a French accent. Then she turns up at his mother's house as his long lost sister - only she has lost the accent. His infatuation with her continues and they have sex, knowing full well their own blood relationship. Other sex, more deviant is mostly hinted at, such as when Lily tells her brother Adam that if he really loves her, he would accept anything from her body. In the city ravaged by acid rain and overrun by mysterious crimson cockroaches, life is spent under the constant watch of the omnipresent DNA21 Corporation.