The Sibling Therapy Series: Seeing the relationships we've learned to overlook
By Erin Runt, LMFT
This is the third blog post in a series of posts called The Sibling Therapy Series: Seeing the relationships we've learned to overlook. This will be a series of ten or so posts about sibling therapy, directed at either the people seeking sibling therapy and sibling relationship knowledge for themselves, or, the people providing these services who want to know more.
If you've become estranged from a parent, or are weighing that possibility, there's a good chance that sibling favoritism is also somewhere in the story.
In some families, the favoritism may have been obvious or made explicit. In many other families, the favoritism probably operated quietly. It may have hidden in a pattern in which one child's distress was taken seriously and another's wasn't. Perhaps there was a different standard for different siblings, where the same behavior meant different things depending on who was doing it. Maybe one sibling’s needs took center stage or were more prominent and prioritized, while another sibling was assumed to be doing “just fine”, since they didn’t seem to need much at all (at least, as far as the adults could tell). Or, maybe one sibling was recruited by a parent to be their confidante, their sidekick, or their preferred companion.
Parental favoritism of one or more siblings is worth discussing whenever there are members of a family who are estranged, because parental favoritism impacts everyone in the family regardless of their position in the family. Understanding how favoritism might have been present in the sibling relationship dynamic can help shed light on why the estrangement between a parent and adult child or between siblings eventually happened, and what each person in the family is navigating now.
How parental favoritism can shape the relationship between siblings
Parental favoritism, which researchers call parental differential treatment, is one of the most consistently documented factors in adult sibling conflict. Geoffrey Greif and Michael Woolley, who spent years studying adult sibling relationships, found it to be among the most significant influences on how those relationships develop and what they carry into adulthood.
It helps to be specific about what this looks like in practice, because favoritism is not always easy to see. Often it shows up in smaller patterns: whose version of events gets believed, whose distress is responded to, who receives the benefit of the doubt. Perhaps it looks like who gets called first, whose achievements are celebrated without complication, who is protected when there's conflict and who is expected to absorb it. It can also look like who gets financial assistance, who gets to have family members show up at events, and who is used as the standard for how the other siblings are measured for their successes or failures.
When a parent or caregiver operates this way, the children in the family organize around it. The child in the favored position, whether they sought that status or not, occupies a structurally different place in the family than the child who isn't. That difference shapes the sibling relationship in ways that have more to do with how the family sorted the children than with either child's personality or choices.
And relatedly, the other members of the family (such as the other parent) are also interacting with that favoritism. They may be trying to balance it out by being closer to the less favored child. Or, they may be reinforcing and validating the favoritism. This is part of why the favoritism can reverberate out to other relationships in the family.
The sibling relationship carries the imbalance
When one child is consistently elevated and another is consistently diminished, the sibling relationship tends to carry that asymmetry. This can look like overt conflict. It can also look like distance: siblings who are cordial without ever being close, who move through family events without quite meeting. It can look like one sibling minimizing the other's concerns, or a loose coalition forming around the favored child that quietly leaves the other on the outside.
For the less-favored sibling, something particularly painful often happens alongside all of this. The family has its own story about why things are the way they are, and that story usually places the responsibility somewhere other than the parent. Over time, the less-favored sibling may have absorbed that explanation, accepting on some level that they are in fact more difficult, more sensitive, or less capable than their sibling. Karen Gail Lewis, whose clinical framework is foundational to sibling therapy, calls this a crystallized role: a family-assigned identity that becomes fixed and self-reinforcing, and that often persists well into adulthood.
The sibling in the favored position is negatively impacted as well, though this may be less clear or harder to identify. Some favored siblings are unaware of the dynamic. Some are aware and genuinely uncomfortable with it. Some have learned to use it. Many may feel a sense of guilt, and many may also fear what they could lose if they were to point it out on their sibling’s behalf. And, being the favored sibling by one parent may at times mean losing the connection to another parent.
How the same dynamic connects to the estrangement
Parent-adult child estrangement tends to develop over time. In many cases, it follows years of a relational pattern that was never adequately addressed and eventually became unsustainable. The favoritism that shaped the sibling relationship is often the same dynamic that, much later, makes the relationship with the parent feel impossible to continue.
This can unfold in different ways. Sometimes it follows a specific rupture: a moment when the less-favored child names what has been happening, the parent is unable to hear it, and the relationship cannot recover from that collision. Often, it is gradual: a slow accumulation of experiences that leads an adult child to conclude that the relationship is costing more than it's giving, and that they aren’t able to be fulfilled or happy while trapped in such a dynamic or role.
For the sibling who stays connected to the parent, this can be genuinely disorienting. The family they experienced may look quite different from the one their sibling is describing, and it may be hard for them to understand where their sibling is coming from. Two children can move through the same family in meaningfully different ways when their positions in that family are different.
What the sibling who stays is navigating
If your sibling has estranged from a parent and you haven't, a particular kind of difficulty can emerge between you. Your experience of the family may genuinely differ from your sibling's, and that gap can make it hard to find shared ground.
Holding your sibling's experience seriously, even without fully sharing it, is one of the harder things a sibling can be asked to do. It means sitting with the possibility that something was harmful to your sibling in ways that didn't register the same way for you. That's different from agreeing with every element of your sibling's account, or from making the same choices they made. It's more about staying curious about an experience that differed from yours, even when the family system didn't encourage that curiosity.
The sibling relationship is often among the casualties of a parental estrangement, and usually through no specific action on anyone's part. Estrangement tends to fracture a family along fault lines that were already present. The favoritism that existed before the estrangement becomes the fault line along which the sibling relationship now has to navigate. Both siblings are typically feeling that pressure, though often in quite different ways.
A place to take this
If you're estranged from a family member, or considering taking that action, it can help to think about your sibling relationships as part of that picture, even if that sibling isn’t the person you are estranged from. How have those relationships been shaped by the same dynamics? Who in your sibling system has a version of the family story that resembles yours, and who has a very different one? How does it impact you to stay connected to a sibling who remains closely aligned with a parent you've stepped back from?
In addition to personal reflection, these are questions and dynamics that can be examined in individual therapy, as well as in family therapy. Family therapists in particular usually have the training and experience in working with family systems to support you to take a wide view lens of your family dynamic for better understanding, as well as to take that understanding into the present day experience you have with your family members now.
Want to learn more?
Additional reading regarding sibling relationships and sibling estrangement:
Who's the Favorite? The Loving, Messy Realities of Sibling Relationships - Catherine Carr
For professionals:
About Erin
I'm Erin Runt, a licensed marriage and family therapist practicing virtually in Illinois, Oregon, Washington, and Arizona (and registered for telehealth in Idaho and South Carolina). My work focuses on adult sibling relationships, couples, and adult family therapy, including the complicated family dynamics that contribute to estrangement. My work has been featured in The Atlantic, in SELF Magazine, and in the book “Who’s the Favorite: The Loving, Messy Realities of Sibling Relationships” by Catherine Carr, specifically on sibling relationships and sibling therapy.
If any of this resonates, I'd be glad to talk. You can reach me through erinrunttherapy.com.
Erin Runt Therapy, PLLC · erinrunttherapy.com
Frameworks referenced: Parental differential treatment discussed with reference to Greif, G., & Woolley, M. (2015). Adult Sibling Relationships. Columbia University Press. The concept of crystallized roles is drawn from the clinical work of Karen Gail Lewis, EdD. See drkarengaillewis.com.