Dear Amy: I am very close with my first cousin “Landon.” Landon is a robust and healthy older man. Unbeknownst to him, we are not actually cousins, in fact, we’re not related at all. Years ago, I asked Landon to submit a DNA sample with the results coming to me, the family historian. That sample revealed that his mother’s husband was not Landon’s biological father. I should note that Landon always had a strained relationship with his “father,” and I remember him as a difficult man. I’m an amateur genealogist and have been able to identify his biological father and relatives. Those still living are a short drive from Landon’s house. Even though he is quite proud of our family history (there’s nothing notable about our tree), he’s paid no attention to the DNA results, assuming they only prove what he’s long believed to be true. I’ve gone to great lengths to protect his privacy while using public databases to research his biological family.