The question of whether Shan’ann COULD have killed her own children will be at the center of the defense case in the Chris Watts trial. Whatever the merits of this case, and in spite of what appears likely, in court a case is only as strong as what can be proven in court.
As much as we’d like to believe a parent killing their child [born or unborn] is monstrous and complete anathema to society, the reality is it’s not only common, it’s an every day occurrence around the world.
About two decades ago, the stats from a UN census showed that in a single year approximately 90 million fetuses or small infants were aborted/murdered throughout Asia. This number isn’t pertinently about mother’s killing their offspring per se, but rather the pre-selection of female first-born children for killing. The abortion-of-girls-scourge is so serious in South Korea, women have to be actively recruited to immigrate to the country because of the mismatch between male and female adults in that country.
What this proves is that cultural incentives [in this case in favor of male first borns] can completely dominate the psychology of adults in terms of their offspring. How the family appears is thus mercilessly enforced within certain cultural and/or socioecomomic constructs.
Child Murder by Mothers: Patterns and Prevention is a peer reviewed [if somewhat dated] research paper published in the US National Library of Medicine. This study pertinently focuses on the mother’s role in the murder of infants. The research paper’s conclusions read as follows:
A mother’s motive for filicide may be altruistic, acutely psychotic, or due to fatal maltreatment, unwanted child, or spouse revenge. In addition, many mothers who do not attempt filicide experience thoughts of harming their child. Maternal filicide motives provide a framework for approaching filicide prevention. Suicidality, psychosis and depression elevate risk, as does a history of child abuse. Mentally ill filicidal mothers have very different risk profiles than mothers who fatally batter their children. Prevention is difficult, because many risk factors, such as maternal depression and social disadvantage, are common among non-filicidal mothers.
In Wikipedia’s introduction to the concept, the final sentences reads, troublingly:
In many past societies, certain forms of infanticide were considered permissible…
But further exploration on the topic reveals all-too-common economic and practical imperatives, both in humans and the animal kingdom. In many societies, including progressive Japan, having twins was considered bad luck, or a taboo, and one or both children were often killed to restore the fates.
Marvin Harris estimated that among Paleolithic hunters 23–50% of newborn children were killed. He argued that the goal was to preserve the 0.001% population growth of that time…A frequent method of infanticide in ancient Europe and Asia was simply to abandon the infant, leaving it to die by exposure (i.e. hypothermia, hunger, thirst, or animal attack).
In at least one island in Oceania, infanticide was carried out until the 20th century by suffocating the infant,while in pre-Columbian Mesoamerica and in the Inca Empire it was carried out by sacrifice…In Kamchatka, babies were killed and thrown to the dogs. American explorer George Kennan noted that among the Koryaks, a Mongoloid people of north-eastern Siberia, infanticide was still common in the nineteenth century. One of a pair of twins was always sacrificed.
According to studies carried out by Kyoto University in non-human primates, including certain types of gorillas and chimpanzees, several conditions favor the tendency to infanticide in some species (to be performed only by males), among them are…the absence of nest construction…
In Eskimo societies, children born in winter were killed by smashing their heads with a rock, or a block of ice, stuffing grass into the baby’s mouth or tossing them into the sea. Research differs, but infanticide among the Inuit was believed to reach as high as 80% amongst some groups.
We can see that though the idea is taboo in Western society, the practice remains fairly common in some present societies too, including those referred to above.
There is a world of difference between killing an infant in a bad season, so to speak, and the wiping out of an entire family – unborn Niko, Celeste, Bella and the children’s mother Shan’ann. No matter how common the killing of a single child is, the annihilation of a family by the head of the household [as is being alleged here] is exceedingly exceedingly rare.
In terms of the particulars of the Watts case, we must also draw a distinction here between infanticide and filicide. I’m not sure that infanticide is the correct definition to use in the Watts case, from the defense case perspective. This is because, strictly speaking, the ages of Bella  and Celeste  place them outside the strict definition. An infant is up to 1 year of age. But the statistics around filicide are nevertheless similar to those of infanticide, until a particular inflection point.
First the definition:
Filicide is the deliberate act of a parent killing their own child. The word filicide derives from the Latin words filius meaning “son” or filia meaning daughter, and the suffix -cide meaning to kill, murder, or cause death.
“Filicide” may refer both to the parent who killed his or her child, as well as to the criminal act that the parent committed.
Now the inflection point. At what age do the statistics show fathers to be the more likely killers of their children?
A 1999 United States Department of Justice study concluded that between 1976 and 1997 in the United States, mothers were responsible for a higher share of children killed during infancy, while fathers were more likely to have been responsible for the murders of children aged eight or older.
Furthermore, 52% of the children killed by their mothers (maternal filicide) were male, while 57% of the children killed by their fathers (paternal filicide) were male. Parents were responsible for 61% of child murders under the age of five. Sometimes, there is a combination of murder and suicide in filicide cases. On average, according to FBI statistics, 450 children are murdered by their parents each year in the United States.
Strangely, in America the trend is the reverse to that in Asia. Male children are slightly more likely to be killed by their mothers, and almost two thirds more likely to be killed by their fathers. Although the data is fairly stale, the preliminary evidence from a purely statistical approach is that fathers are significantly less likely to kill their own children than their mothers, especially when they’re female.
Just as in infanticide, spousal revenge is also a potential factor in filicide. Whether these numbers or trends are fielded in court by Chris Watts’ defense team or not, what remains clear is that the reverse is also true. If the case is made that one parent killed their children out of spousal revenge, the possibility exists that the other parent could just as easily be culpable of the same accusation. What really has to be shown is which spouse had the bigger bone to pick with the other, and ultimately, if it was revenge, revenge for what?