The Brood

Psychotherapist Hal Raglan runs the Somafree Institute where he performs a technique called "psychoplasmics", encouraging patients with mental disturbances to let go of their suppressed emotions through physiological changes to their bodies. One of his patients is Nola Carveth, a severely disturbed woman who is legally embattled with her husband Frank for custody of their five-year-old daughter Candice. When Frank discovers bruises and scratches on Candice following a visit with Nola, he informs Raglan of his intent to stop visitation rights. Wanting to protect his patient, Raglan begins to intensify the sessions with Nola to resolve the issue quickly. During the therapy sessions, Raglan discovers that Nola was physically and verbally abused by her self-pitying alcoholic mother, and neglected by her co-dependent alcoholic father, who refused to protect Nola out of shame and denial. Meanwhile, Frank, intending to invalidate Raglan's methods, questions Jan Hartog, a former Somafree patient dying of psychoplasmic-induced lymphoma.
Frank leaves Candice with her grandmother Juliana, and the two spend the evening viewing old photographs; Juliana informs Candice that Nola was frequently hospitalized as a child, and often exhibited strange unexplained wheals on her skin that doctors were unable to diagnose. While returning to the kitchen, Juliana is attacked and bludgeoned to death by a small, dwarf-like child. Candice is traumatized, but otherwise unharmed.
Juliana's estranged husband Barton returns for the funeral, and attempts to contact Nola at Somafree, but Raglan turns him away. Frank invites his daughter's teacher Ruth Mayer home for dinner to discuss Candice, but Barton interrupts with a drunken phone call from Juliana's home, demanding that they both go to Somafree in force to see Nola. Frank leaves to console Barton, leaving Candice in Ruth's care. While he is away, Ruth accidentally answers a phone call from Nola, who, recognizing her voice, insults her and angrily warns her to stay away from her family. Frank arrives to find Barton murdered by the same deformed dwarf-child, who dies after attempting to kill Frank.
The police autopsy reveals a multitude of bizarre anatomical anomalies: the creature is asexual, supposedly color-blind, naturally toothless, and devoid of a navel, indicating no known means of natural human birth. After the murder story reaches the newspapers, Raglan reluctantly acknowledges that the murders coincide with the sessions relating to their respective topics. He closes Somafree and sends his patients to municipal care with the exception of Nola.
When Candice returns to school, two dwarf children attack and kill Ruth in front of her class, and abscond with Candice to Somafree. Frank is alerted of the closure of Somafree by Hartog. Mike, one of the patients forced to leave the institute tells Frank that Nola is Raglan's "queen bee" and in charge of some "disturbed children" in a property work shed. Frank immediately ventures to Somafree. Raglan tells him the truth about the dwarf children: they are the accidental product of Nola's psychoplasmic sessions; Nola's rage about her abuse was so strong that she parthenogenetically bore a brood of children who psychically respond and act on the targets of her rage with Nola completely unaware of their actions. Realizing the brood are too dangerous to keep anymore, Raglan plots to venture into their quarters and rescue Candice, provided that Frank can keep Nola calm to avoid provoking the children.
Frank attempts a feigned rapprochement long enough for Raglan to collect Candice, but when he witnesses Nola give birth to another child through a psychoplasmically-induced external womb, she notices his disgust. The brood awakens and kills Raglan. Nola then threatens to kill Candice rather than lose her. The brood goes after her, Candice hides in a closet, but the brood begins to break through the door and try to grab Candice. In desperation, Frank chokes Nola to death, and the brood dies without its mother's psychic connection. He carries Candice back to his car and they drive off, but it is hinted that the events she endured result in the same phenomenon her mother experienced: a pair of small bumps are seen growing on her arm.

Question: Ruth is Frank's daughter's what?
Answer: Teacher