Actually the movie is NOT based on a true story, but it shares similarities with two sisters with the last name Ayala and what they went through. I looked it up on idmb. Also it is not about anyone with any personality disorders. It's about 2 young girls who are sisters and one is diagnosed with cancer. She needed a transplant and the parents weren't matches. So they genetically created another daughter to be a match for what the sick child needs.
"My Sister's Keeper" is a movie that is based on a true story of two sisters and their journey toward self-discovery and understanding. It tells the story of a woman who must learn to balance her career and personal life with looking out for her older sister, who also faces her own struggle with bipolar disorder.