There were similarities and differences. It was the husband who was the religious individual, not Andrea. She seemed to the layman like me to be on a cocktail of drugs:
Russell Yates has said that his wife had taken four drugs for her emotional difficulties. One of them, Haldol (haloperidol) is particularly powerful, utilized, according to a mental health monograph, “in the management of manifestations of acute and chronic psychosis, including schizophrenia and manic states.” Andrea started using the drug, often prescribed for people hearing voices or thinking delusionally, after the birth of her fourth child.
At the time of the June 20 tragedy she was taking Effexor and Remeron, both anti-depressants, and had been previously taking Wellbutrin, another anti-depressant, as well as Haldol. Yates told the press that his wife had been in therapy, but was not at the time of the killings. “He said they had recently talked about her going into therapy again but she had not got around to it yet,” the Houston Chronicle reported.
Her symptoms seemed to be similar to Sheila's:
Yates also explained that the birth of the couple’s fifth child and the death of his wife’s father had triggered another episode of extreme depression. She had become withdrawn and “robotic” in her movements in the three weeks before the children’s killings, he said. Her brother has told the press that Andrea put a knife to her own throat while visiting her mother’s house this spring—presumably after her father’s death—and again threatened to kill herself. Cases of women undergoing post-partum depression are relatively common; post-partum psychosis of the sort Andrea Yates apparently suffered from is extremely rare.
She deferred to her husband on all matters: it was he who wanted a large family. She felt trapped in the home, exhausted through teaching and a low self-esteem:
The details that have been made public about the few months leading up to June 20 paint a picture of an increasingly desperate Andrea Yates, subject to psychotic episodes and severe depression, struggling to live up the ideal “Christian” lifestyle, trapped with her five young children twenty-four hours a day . And instead of seeking serious professional, psychiatric help, the couple could only call on more of the same, stultifying fundamentalist dogma.
If you believe Sheila guilty then the motive is probably the same for both:
It is possible that the couple hoped a fifth child would help Andrea through her mental difficulties. But the depression, despite her best efforts, persisted and deepened. Perhaps she concluded that her “bad” thoughts and behavior were contaminating her children. Psychologists have defined a mental state they term “altruistic filicide” (filicide means the murder of a child by a parent), which usually involves a mother killing her children because she believes she is doing the best thing for them, that they are literally better off dead.
