Adult Sibling Alienation: Who Does It and Why (2023)

Adult Sibling Alienation: Who Does It and Why (1)

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Parental alienation occurs when one parent, the alienator, turns the children against the other. Sibling alienation occurs when one adult sibling wants to push aside another. While sibling alienation can occur at any point, one sibling may be especially tempted to alienate another in order to gain control of care-taking or inheritance outcomes with aging parents.

A targeted individual, whether the alienation targets an adult sibling or a co-parent—as well as judges, lawyers, mental health professionals, and other family members—must be knowledgable about alienation to bring it to a halt before it results in unfair and harmful outcomes, and especially if the decision-making ends up in court. Alienating individuals often issue false charges, so the courts are highly likely to become involved

Psychologist Jennifer Harman and colleagues established in a landmark academic article that parental alienation is a serious form of domestic abuse. Poisoning children against the other parent creates long-lasting and potentially devastating mental health consequences for children.

Similarly, adult siblings (or siblings-in-law) who attempt to poison others about one of their siblings, can produce long-lasting divisiveness within the family, physical as well as emotional harm to the elderly parent, and profoundly emotionally and financially draining court battles.

What Motivates Sibling Alienation?

The motivation of an adult sibling who falsely claims either that another sibling is harming the aged parent in their care, or of one who falsely claims that another sibling is receiving more than their share of the inheritance, generally stems from several roots. Sibling rivalry and wanting to show that mom or dad loved them more than their sibling may be one source. Another source of this alienation can be money.

An alienating sibling, for instance, may prefer for the parent to die rather than for the parent's money to go to expensive medical interventions or caretaking that would whittle down the inheritance.

After death, inheritance issues come directly into play. Because alienating siblings typically believe that they are entitled to more of the inheritance than the other siblings, they spread negative innuendos and false accusations regarding the targeted sibling to convince others of their view.

Lastly, one important indicator of alienation is longstanding hostility. If a sibling has for many years been spreading negative innuendos and false accusations about the targeted sibling, trying to isolate the targeted sibling from others in the family, odds are very high that alienation will be exacerbated near the time of the last parent's death. This pattern can help lawyers and judges to diagnose alienation accurately.

The alienating sibling usually feels unfairly treated because what they feel entitled to is, in fact, an erroneous and excessive expectation. How does this excessive expectation develop?

In general, most adult siblings seek to interact cooperatively in caretaking. They show appreciation for the sibling who bears a larger share of the caretaking responsibilities. With regard to the inheritance, they seek a fair distribution of their parents' financial and other assets.


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Those who, instead, participate in alienation unfairly attack the sibling that counters their preferences. This person may also have significant character pathology, though not always. This may include:

  • Narcissism. Narcissism leads to the belief that they deserve more than their siblings. Narcissism is selfishness: "It's all about me." "What I want matters more than what anyone else wants." "The rules don't apply to me because I matter more than others." In some cases, narcissism can be a part of Narcissistic Personality Disorder (NPD).
  • Borderline personality disorder (BPD). Those with BPD have a tendency toward hyper-intense emotions and hypersensitivity to interpersonal relations. This can be expressed in excessive anger and hostility towards others. These strong emotions can make others in the family feel that they must walk on eggshells. In addition, people with this disorder tend to lash out at those closest to them, such as family members.
  • Willingness to lie. Lying can be a part of a variety of clinical diagnoses. Some with mental health disorders may quickly believe their own lies, enabling them to poison others with false accusations about the targeted sibling without pangs of conscience.

An alienating sibling initially spreads their tainted view of the targeted sibling to other family members. They may then expand the spread of these false narratives to others who have an association with the elderly parent—to the parent's friends and relatives, paid caretakers, doctors, nurses, and rehabilitation center workers—to undermine the trust toward the targeted sibling of these collateral members of the parent's world. This poisoning also preps collateral figures so they will side with the alienator against the targeted sibling in eventual court battles.

Family Dynamics Essential Reads

Why Only Children Often Go to the Head of the Class

Are You the Family Black Sheep? Here's How to Deal

Legal Battles

When these cases go to court, what do legal professionals need to know?

Alienating siblings often misuse the court system to challenge the targeted sibling's medical decision-making authority and also to unfairly expand their own inheritance portion. The legal system gets called on in these cases, but may not be prepared for what they're witnessing. Lawyers, judges, and court-appointed guardians and conservators can be aided in the identification of alienation by being on the lookout for three phenomena in particular:

1. Lies

Alienators often lie. They make up facts to fit their case. Lawyers and judges need to be on the alert for a pattern of lying to identify a potential alienating sibling—conveying false reports about the targeted sibling to other family members, submitting false claims to the police, telling lies about the targeted sibling to caretakers, or issuing court motions such as for elder abuse or theft from the elder's bank account. When several accusations such as these have no basis in reality, a diagnosis of alienation is highly likely to be appropriate.

2. Projection

Projection is the clinical term for accusations that in fact describe the accuser rather than the accused. When an alienating sibling describes the targeted sibling as greedy, for instance, it may be possible that the greedy one is actually the accuser.

3. Selfishness

Alienators look only for their own gain with little to no concern for others in the family. For instance, an alienator in one family I have worked with wanted medical power of attorney in order to block the sibling that was devotedly taking care of her mother from using the parents' money to hire around-the-clock caretakers for her post-stroke functioning. The alienating sibling wanted to transfer their mother to a nursing facility, a money-saving option that would have provided far less attentive care and to which their mother was adamantly opposed.

In another case, an alienating sibling removed almost all of the valuable art from the parent's home before allowing any of the siblings to divide up their parents' belongings.

In another extraordinarily selfish example, an alienator engineered changes in the mother's will just prior to the mother's death, transferring ownership to herself of the home that was to have been left for their mother's severely disabled granddaughter.

Beware: One Common Error

With alienation, the ideas that "the truth lies somewhere in between" and that "it takes two to tango" both are erroneous. Think of a bank robber and a bank teller. There is clearly one bad actor; the bank teller is just in the wrong place at the wrong time.

Become fully informed on parental alienation, and by extension, also on sibling alienation. To learn more about alienation and the several forms in which it can be enacted, please feel welcome to explore my prior posts on this subject. This article by estate planners also has useful information.

Information is power.

Emotional Survival

Having lies spread about you can be distressing, frightening, and infuriating—and all the more so when the lies aim to deprive you of your rightful financial inheritance. Being able to stay in the calm zone will take major skills. My book Prescriptions Without Pills: For Relief from Depression, Anger, Anxiety and More addresses this challenge. Hopefully the book, and this article also, will prove to be helpful for you. Of the many challenges people can face in life, Adult Sibling Alienation (ASA) is right up there toward the top.

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