Ah, the eternal "Molly question." The Law & Order: Criminal Intent Wiki states that Molly (the curly-haired little girl from the opening scene in the episode "Faithfully" who offers Goren some butterbeans) is Donny's half-sister, and I had gone along with that until just recently. However, given that "Faithfully" follows "Frame," in which Frank Goren is killed, my thoughts are now that Molly is a member of William Goren's side of the family. The family scene opening "Faithfully" shows Goren sharing dinner at what seems like a rural home with an older man and woman, a younger man, and two children, one of whom is Molly. The episode just states they are his "family," hitherto unmentioned. My theory is that the older woman is probably his father's sister, and she married a man named Fry, hence the name "Fry" on the return address of the envelope Goren receives in the mail in the final scene. The younger man is probably his cousin, and Molly and the little boy are the cousin's children, so that Molly is Bobby's first cousin once removed. My guess is that William Goren was the "wild child" of the family, probably left home at an early age for New York City, and the family had become estranged from him, but when Frank died, Goren's aunt came to Frank's funeral and he reconnected with them. (Perhaps a similar explanation was edited from the final cut of the episode.)