Empathy - Hoa Pham

A science-fiction novel involving clones, a psychic, and empathy as a recreational drug.
We have always been we. Then they forced us to become you and I.
Empathy consists of two stories told in parallel. 

Vuong is one of five Vietnamese clones that have come of age at 25. The Department in Hanoi is allowing them to meet after being separated for twenty years. Lian has murdered her foster father after being forced to eat meat. Geraldine is dying of cancer in Australia. Giang and Khanh were brought up together as twins in New Zealand and are telepathic. They have been used for research over their lifetimes. Vuong discovers that the data kept on all of them has been used to develop empathy, the latest party drug.
My meets Truong in Berlin who introduces her to empathy which makes the user supersensitive to other people's feelings. My's mother is a cleaner at CHESS, a multinational chemical company, and My comes to believe...