Pliny the Elder did not marry and had no children. In his will, he adopted his nephew, which entitled the latter to inherit the entire estate. The adoption is called a "testamental adoption" by writers on the topic, who assert that it applied to the name change only, but Roman jurisprudence recognizes no such category. Pliny the Younger thus became the adopted son of Pliny the Elder after the latter's death. For at least some of the time, however, Pliny the Elder resided in the same house in Misenum with his sister and nephew (whose husband and father, respectively, had died young); they were living there when Pliny the Elder decided to investigate the eruption of Mount Vesuvius, and was sidetracked by the need for rescue operations and a messenger from his friend asking for assistance.