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Sibling Studies: The good, the bad, and the contradictory

Date Last Revised: 
August 20, 2010
Date Published: 
December 17, 2007
Teresa J. Foden
IAN Assistant Editor
Kennedy Krieger Institute

Boy with Asperger's and his sister on trampolineAs some autism researchers pore over brain MRIs in labs and other researchers closely observe children in natural play settings, noting in micro-detail every element of every interaction, and as parents scour the landscape of cyberspace for the latest and greatest in treatment methods, many an eye is turning to the role of siblings. The sibling bond is a key component of the developing personality of children, and there is research showing that this holds true when one of the children has a disability. However, there is considerable debate about how this relationship molds the typically developing siblings and the children with autism alike, and whether this sibling effect is positive or negative. 

Adding to the complexity of the search for answers is the sheer variety of labels that comes under the umbrella of autism spectrum disorders (ASDs): autism, pervasive developmental disorder-not otherwise specified (PDD-NOS), and Asperger's disorder, to name a few. These children exhibit a puzzling array of deficits and strengths which even the experts can't completely agree on, all spread over a wide spectrum.

The good, the bad, and the contradictory

Undoubtedly, the interplay between siblings profoundly affects each participant's personality, social, and intellectual development. However, exactly how that plays out, and exactly what interventions might support positive sibling interactions, remains murky. Studies are chock-full of reports that the path for siblings of children with ASDs is fraught with developmental landmines.

Some studies show that siblings of children with autism face a particularly daunting task in forming a healthy sibling bond, especially given the lack of social interest likely from many children with ASDs. The adjustment of these siblings varies greatly, with a number of them faring significantly worse than siblings of children with other disabilities. This feeds nagging concerns that typically developing siblings in families with autism may be more vulnerable to behavioral problems, speech and language disabilities, anxiety, and depression and other mood disorders. The genetic component of autism also must be considered, as some studies show that the siblings of children with ASDs are at a higher risk for ASDs and related impairments. 1,2

Parents participating in one 2007 study described social deficits that appeared in siblings shortly after their first birthday. 3  In their summary, the researchers suggested that in some cases, speech and language therapy, as well as behavioral therapy, may make sense for siblings of children with autism. The report concluded with a recommendation for future studies tailored to monitoring these siblings over time.

A study spanning three years in the mid-1990s compared the adjustment of siblings of children with PDD, Down syndrome, or no disabilities. The findings were bleak: "Significantly more difficulties were found in the siblings of children with PDD compared with the other two groups." So there it was: siblings of children with PDD struggled more than other siblings, even more than those of children with another disability, Down syndrome. Not only that, but factors that eased stress in the other two sibling groups, such as marital satisfaction and lack of parental depression, had no noticeable protective effects on the group of siblings of children with PDD. 4  However, one study did find that large family size appears to contribute to the healthy adjustment of siblings of children with autism. 5

But there is reason for hope. A growing body of research shows that some typically developing siblings outright benefit from their relationships with children with autism. These siblings speak of a certain pride in "teaching" their siblings, and may have higher scores on self-esteem, empathy, and maturity measurements. One study demonstrated that the child with autism was more social with a typically developing sibling than with parents trying to bridge the gap between generations, suggesting that the natural interactions in these sibling relationships potentially benefit both children. Other studies show that siblings of children with autism are likely to take the lead role in the relationship, even when they are the younger in a pair of siblings. They seem to actually tailor their behaviors to maximize the interaction for both themselves and their sisters and brothers.

Siblings of children with autism, Down syndrome, or no disabilities participating in a 2001 Canadian study described less quarreling and competition in the families with a child with a disability, whether autism or Down syndrome, than in families without children with disabilities. 6  A report by the same researchers the following year found that siblings of children with autism were not at increased risk for maladjustment. The researchers noted that more than three-quarters of the families in the study attended support groups, and suggested that siblings' increased access to information and social support may contribute to their positive adjustment. However, the researchers made a distinction between brothers and sisters: "sisters of children with autism had the highest average social competence scores, whereas brothers of children with autism had the lowest social competence scores."  7

A 2004 study compared three groups: siblings of children with autism, siblings of children with mental retardation, and siblings of children with developmental language disorders. The results led researchers to suggest that "siblings of children with autism are, for the most part, surprisingly well adjusted."  8  A year earlier, several of these same researchers, reporting on their study of school-aged siblings of children with autism, reported some encouraging news: language impairments that appear in some young siblings of children with autism may all but disappear with time. 9

In another study, published in the Journal of Autism and Developmental Disorders in late 2007, researchers observed social interactions of siblings of children with autism or Down syndrome during a one-year period. They concluded: "With their siblings at least, children with autism appear to develop in line with other children, albeit more slowly.... A rich vein of information can be gained from examining the way such relationships are played out in their natural contexts."  10

Siblings spend their childhood "sharpening their teeth" on each other. And as hard as it may be to watch, it's all in the name of a crucial developmental outcome: producing self-sufficient adults capable of weathering most of life's challenges. However, stir an ASD child into this volatile mix, already characterized by magical thinking, interdependence, and sometimes intense rivalry, and you have...well...nobody really knows. 

The sibling bond in a petri dish

As with much of research into the causes and effects of ASDs, the results in sibling research studies seem contradictory. Perhaps adding to the overall feeling of consternation, the findings sometimes don't ring true for families experiencing autism in the most natural lab of all, the home. But with the sibling relationship playing such a central role in family life, we can't help but wonder how to maximize its gifts and minimize its burdens. There is something just out of reach, something pure, about the sibling bond. Adults are largely relegated to the outside, unable to step back to a time when personality was so raw and so fluid. The words of an oft-cited study of sibling bonds, going back more than 30 years, still hold true today: "Siblings collude and align with each other.... The sibling relationship is seen as a life-long process, highly influential throughout the life cycle."  11 

In its "Living with Autism" section online, the Autism Society of America sums up one of the central dilemmas of the sibling of a child with autism: "Your child's attempts to play with his/her brother are probably rebuffed by his ignoring her, fall flat because of his lack of play skills, or end abruptly because his tantrums are frightening. How many of us would keep trying to form a friendship with someone who turned her back when we spoke to her, or, even worse, seemed angry when we approached?"

Researchers who choose this field of inquiry are delving into the intricacies of how sibling roles emerge in these families and how they affect the developing personality. This body of work is bringing some of the questions, if not the answers, into sharper focus. Among those are:

  • How do siblings of children with autism fare in the long term?
  • Are children with autism capable of benefiting from a relationship with a typically developing sibling?
  • And, perhaps among the most pressing questions for parents, how can the positive aspects of that relationship be fostered by those adults on the outside looking in?

ASDs impose major stresses on the family, siblings included, and the "hidden" nature of these disabilities often serves only to amplify what otherwise would be typical family responses to stress. As one group of researchers put it more than 15 years ago: "Living within this family climate, the risks for emotional and behavioral problems for siblings must be evaluated, along with their intrinsic strengths, to plan preventive interventions for these children."  12

Researchers of a recent study that took aim at the notion that siblings of children with autism are doomed to a life of maladjustment and resentment acknowledged studies showing a high potential for difficulties in these family relationships. But ultimately the study concluded that the siblings of children with autism appeared to have a stronger self-concept and more maturity than siblings of typically developing children. 13

The Journal of Autism and Developmental Disorders study, mentioned earlier in the text, found that typically developing siblings tended to "stage-manage" during play with children with autism. "Siblings of children with autism may use imitation in free play to encourage interaction, further supporting the notion that they 'stage-manage' the relationship by tuning into the behavior of the child with autism."  14  A 1995 study, comparing sibling interaction in relationships involving a child with autism or Down syndrome, found that though children with autism may have interacted less with their siblings, they did respond to social overtures from their siblings. "Sibling encounters provide a unique opportunity for such children to learn about social relationships."  15

Another pattern emerging from some of the research is the tendency of some siblings to reverse roles in relationships with children with autism and other disabilities. In these cases, the typically developing sibling may assume a dominant/teaching role regardless of birth order. However, though the role of typically developing younger siblings usually involves imitation of the older sibling, the opposite proved to be the case in families with autism, according to the Journal of Autism and Developmental Disorders study: "In pairs including a child with Down syndrome, the disabled child maintains the interaction by imitating the sibling. However, in the pairs including a child with autism, the pattern was reversed."  16  Within the context of the sibling relationship, the typically developing sibling and child with autism may be able to tune into each other on a level not often observed in interactions with their family or peers.

Generally, researchers agree that insights into the relationship between typically developing siblings and their brothers and sisters with autism will help to unearth the key clues to solving the mystery of ASDs. One research review in 2005 summed up the growing sense of urgency among many researchers, caretakers, and treatment providers with these words: "Few disorders in children pose a greater threat to the psychosocial well-being of families than autism because the behavioral characteristics of this disorder tax even the strongest family systems." 17  Given the rising numbers of children with autism and the possible mental health risk for their siblings well into adulthood, studies on adult siblings of those with autism could join the other research priorities sure to take center stage in the coming years.

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