Josef Mengele was an abhorrent character who conducted medical experiments on live human beings without consent. He is known for doing all manner of terrible things, but the focus on this book is his studies on both identical and fraternal twins that he managed to snatch away from their families during death selections. A lot of these twins were children, somewhere in the neighborhood of 3,000 of them. Typically, he used one twin to test on and one as a control subject. One twin was subjected to injections of diseases, surgeries, disfigurements, and painful conditions to see how much they could tolerate. Some were even forcefully impregnated via insemination, abortions were performed, and sterilization techniques were practiced. They were often also subjected to unnecessary amputations. This man was vile. I cannot imagine what these people went through and thought, and how terrible it would be to be experimented on without consent or knowing what may happen to you. This book was gross and terrifying, but was a good read.