Looking to identify a book. I read an anthology somewhere around the year 2,000 give or take a couple of years. They were short stories, I think written by different authors. The idea was that people had personalities implanted in their minds- I don't remember if it was a hand-waved time travel actual recording of the personality, or if it was an artificial reconstruction. Actually, writing this question out, I think the idea was tied to memory stored in DNA which could be injected into someone. I seem to recall that the awareness of the personalities varied from story to story, from full-on minds that could be conversed with (like the Sector General Pathologists) to something more subconscious.
The stories ended up being variants on the old idea of getting to meet anybody from history that you wanted and them helping improve your life.
I do not remember many of the stories. I think one of them was a person getting DNA from the Shroud of Turin injected in order to bring back Christ. As it turns out, the Shroud is fake, and instead the personality of a medieval con-man is brought back, who realizes that all he needs to do is to pretend that yes, he is indeed the returned messiah...
Another one was a guy who is obsessed with Leonardo Da Vinci. I seem to recall the story started out with him building one of Da Vinci's perpetual motion machines, and believed that were Da Vinci alive today with access to modern materials, the machine could indeed run. As memory serves, he has the personality implanted. I don't think Da Vinci's personality is consciously present, but I seem to recall a scene where the man is repulsed by his girlfriend before remembering that Da Vinci was homosexual and must be affecting his tastes. In the end, he wakes up and is about to head out and hears a noise. He goes to his kitchen to see the perpetual motion machine ticking along, having been successfully built in his sleep.
Snippet of memory that I think was from a different story with Lord Kelvin (it may have been from the Da Vinci story though) where the main character is "talking" with the personality. The personality is stunned by the modern world and modern technologies and keeps asking questions, only to be rebuffed by the main character being annoyed by the incessant questions. It was a wake up call to the main character of how ignorant they were of modern day technology.
There may have been a story about a woman who was always walked on by people in her life and the injected personality gave her the strength to overcome her personal challenges.
Speaking of which, I seem to recall the stories taking place more or less present day. I think the book was new when I read it.