"Down to the Bone", the last of Justina Robson's Quantum Gravity (horrible name) books. Robson is a writer who doesn't get the fame she deserves, probably because none of her books have robots, lasers or spaceships in. But she produces genuinely original F/SF, which is pretty rare. She also does much better characterisation than most SF writers, although that's not hard. But this series is hard to follow at times, not helped by spreading the reading of the five books out over about six years.