Eve

When two fathers on opposite sides of the country are inexplicably murdered at the exact same time in the exact same way, Mulder and Scully find that their eight-year-old daughters are perfect twins (Erika and Sabrina Krievins) and were created in order to continue The Litchfield Experiment, a eugenics project of the 1950s which produced cloned boys named Adam and girls named Eve who have heightened strength and intelligence, but are prone to psychotic behavior. Guest starring Harriet Sansom Harris.