I wanted to know how people with no medical history whatsoever - like an adopted child or an orphan - fill in the gaps of their family history? Does anybody know the kind of details that are revealed by genetic testing? For example, I have a friend who lost her entire family during an earthquake as a child and has no records available of either of parents family medical history. But she remembers blurry stories about her mother possibly being a vanishing twin survivor and now that she's getting married, she's worried she might have inherited it. Will complications like that be revealed via early testing?