In 2336, a one-person shuttle crashed on Cor Coroli IX, and T'Pas was the first individual to respond. The occupant of the shuttle was a Romulan smuggler named Rajari, who subsequently raped and impregnated T'Pas. She gave birth to a daughter, Soleta, the following year.
T'Pas and Volak both withheld the truth of Soleta's origins until her adulthood. When she learned the truth in 2362, it endangered Soleta's Starfleet career, and she took an extended leave of absence, to T'Pas' displeasure. (NF short story: "Revelations")