Identical Strangers (Book #19)

Identical Strangers (Elyse Schein and Paula Bernstein, 2007) tells the story of identical twins separated, not at birth, but after six months together in foster care. They rediscovered each other in their mid-30's when Elyse went looking for more information on her background. The sisters got along well from the beginning, though with occasional rocky moments, and together they went sleuthing to find out more about who they were--only to discover the unpalatable truth that they were most likely separated deliberately as part of a study researching genetic vs. environmental components of mental illness among identical twins with a family history of instability. (Such a study would never be approved now, but was considered marginally acceptable when they were born in 1968.)