Why people kill their parents according to a criminologist

As the murderous Menendez brothers return to the spotlight, a criminologist examines the possible reasons behind parricide

Monsters: The Lyle and Erik Menendez Story, the recent Netflix drama series, has captivated just as much audience attention in recent weeks as the real-life case did 35 years ago. 
It was in 1989 that Lyle and Erik Menendez killed both their parents, shooting them repeatedly at their family home in Beverly Hills. The pair were later found guilty of murder after a lengthy televised trial. In the recent Netflix drama, their story is told from various perspectives, with a whole host of possible motives examined.
Initially, the show portrays the brothers as vapid Los Angeles rich kids, so spoilt and devoid of empathy that killing their parents appears as little more than an amusing distraction. But as the story unfolds, we learn the brothers are victims of lifelong mental and sexual abuse by their overbearing father, José. While police and prosecutors suggest the brothers killed their parents to access a huge inheritance (Lyle and Erik indulged in wild spending sprees shortly after the murder), their defence attorneys insist the killings were carried out in self-defence. 
As one of the most high-profile incidents of parricide in modern history, the Menendez brothers’ actions shaped popular perceptions of child-to-parent murder. “The Menendez case is shocking precisely because it is atypical,” says Rachel Condry,  professor of criminology at Oxford University and co-author (with Caroline Miles) of the report Parricide, Mental Illness and Parental Proximity. “It provided a compelling narrative because it was [set] against a backdrop of wealth and glamour in LA. But most incidents of parricide in the UK are more run-of-the-mill by comparison. They are often the result of long, complex relationships between parents and mentally-ill adult children. It is extremely rare for two siblings to conspire. Revenge killings are not common and the use of guns even less so.”
Still, incidents of parricide are not as unusual as many may think. Between 2003 and 2016, there was a steady average of 21 cases of child-to-parent murder in England and Wales each year, accounting for 5 per cent of all homicides. “It is a taboo subject and often misunderstood,” says Condry. “But more needs to be done to understand and prevent it. If 21 people were dying consistently every year of, say, minibus crashes, the Government would want to know exactly why so they could take preventive measures. With parricide, this just isn’t happening.”
In the Menendez case, father José was thought to be the victim of a revenge killing by his sons, whom he sexually abused for many years. Why Lyle and Erik also chose to murder their mother is less clear: the show floats various theories, including her role as an enabler or the fact she posed an obstacle to their inheritance.
In the UK, the vast majority (88 per cent) of homicide victims are men. But in cases of parricide, the victims are just as likely to be mothers as fathers. It tends to be older sons (an average age of 38) who murder their mothers. “It is generally older mothers around their mid to late 60s who are the victims,” says Condry. “This is often because they are caring for adult sons who are at the extreme end of mental illness. Mothers are often the ‘last woman standing’ in these situations, where a son has alienated everyone else in his life and needs support from his mother – not just in terms of his health but his day-to-day life, such as keeping appointments. When these relationships become violent, there are not enough systems in place to alert authorities or help the mother. Often, mothers are less likely to report their son’s violence.”
The Menendez brothers are depicted in the show as calculated (if clumsy) planners. The brothers take inspiration from Billionaire Boys Club, a film depicting parricide. They buy firearms and plan their alibis over a lengthy period of time, before carrying out the killings. According to Condry, such forethought is very rare.
“Parricide is usually not very calculated,” she says. “More often, it’s a case of a spontaneous violent episode getting out of control. In all of our research in the UK, we have not seen cases in which siblings have conspired to commit parricide. They have always been an individual child acting alone.”
José Menendez was an executive at RCA Records and had reportedly accumulated over $14 million in wealth. In the Netflix series, Erik and Lyle are shown indulging in a wild spending spree after their parents’ murder. At the time of their arrest, the media narrative was centred on the brothers’ financial greed – but parricide in pursuit of inheritance is rare. “People often assume people kill their parents for money,” says Condry. “But that’s because one-off cases like the Menendez murders make sense of what is a very disturbing crime that most people don’t want to think about. Understanding it to be a transactional killing for financial gain provides a simplistic explanation. The reality is perhaps more scary – sometimes people with extreme mental illness kill their parents in a state of rage or delusion.”
Erik and Lyle Menendez’s crimes were characterised by their legal teams as acts of self-defence against their abusive father. So-called “retaliatory killings” are less common in the UK, where 74 per cent of children who kill their parents have a diagnosed mental illness. In the vast majority of these cases, their mental condition is deemed to be legally causative. “Our data suggests parricide in response to parental abuse is more rare here than in the United States,” says Condry. “This might be because the crime investigations don’t always look back into family history and establish if abuse was present. But what we see more of are adult children who suffer from the extremes of mental illness such as delusion and schizophrenia. Their parents are often responsible for their care, which can put them in a very vulnerable position. Not enough is done to safeguard parent carers of mentally-ill adult children.” 
Of the 21 cases studied in detail in Condry’s report, the perpetrator in all but one had a serious mental illness. Most of the cases involved a parent caring for a mentally-ill child, while five cases involved an adult child caring for a parent. The majority of perpetrators were given hospital orders for mental health treatment rather than handed prison sentences.
A 76-year-old woman was killed by her 44-year-old son. He was found wandering the streets naked after the killing. He said he thought his mother was a witch and had mutilated her body using various weapons, even decapitating her. She was found on a bed in her home, where he was also living temporarily. He had been diagnosed with schizophrenia at the age of 18 but had stopped taking his medication some weeks before the homicide. 
His mother had not been consulted on this decision, which doctors made, and yet she had been expected to monitor his condition and report any problems. A plea of manslaughter on the grounds of diminished responsibility was accepted, and he was sentenced to a hospital order under S.37 Mental Health Act with a restriction order attached. It appeared that some services knew he had been previously violent towards his mother. An ambulance was called to the property for another health issue shortly before the day of the homicide. He was angry and aggressive towards his mother in front of the crew, and she told them she was very frightened of her son and he had the potential to physically hurt her. Although they made a referral to adult safeguarding services, this was not appropriately investigated or responded to.
Case taken from  “Parricide, Mental Illness, and Parental Proximity: The Gendered Context Of Parricide in England And Wales” by Rachel Condry, Caroline Miles and Elspeth Windsor