Doctor's Family Program Beta-Rho

From Memory Alpha, the free Star Trek reference

Doctor's Family Program Beta-Rho was a holoprogram written by the Doctor to create for himself a holographic family in an attempt to understand what it was like to have one.

In the original program, the Doctor had a wife, Charlene, and two children, Jeffrey and Belle. In the original version of the program, the Doctor's family was an unrealistically agreeable, 'ideal' family. Lieutenant B'Elanna Torres edited the simulation, giving it a greater degree of randomness and also adding realistic character flaws and disagreements between the family members. Torres' version also allowed for an unexpected tragedy, which caused the Doctor a great deal of unexpected confusion and pain. (VOY: "Real Life")