Definition and research guide
This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.
Content available: 4 complete abstracts (803 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.
Definition
Persons or animals having at least one parent in common. (American College Dictionary, 3d ed)
Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.
Also known as: Sibling; Brothers; Brother; Sisters; Sister.
Where it fits in the MeSH classification
- Broader topics
- Family; Persons
Research landscape
PubMed indexes 14,813 records tagged with the MeSH heading “Siblings” (counts retrieved 2026-10-31). 3,551 of them (24.0%) were published from 2020 onward, and the busiest period so far is 2010-2019 with 6,567 records.
Reviews account for 725 records (4.9%) and meta-analyses for 83. Randomized controlled trials number 138 (0.9%) as a share of all records on the topic. Randomized trials make up only a small share of this literature, so much of what is known comes from laboratory, observational or descriptive work.
Show the data
| Period | Records |
|---|---|
| through 1999 | 958 |
| 2000-2009 | 3,737 |
| 2010-2019 | 6,567 |
| 2020 onward | 3,551 |
Publication-type chart data
| Type | Records | Share |
|---|---|---|
| Reviews | 725 | 4.9% |
| Meta-analyses | 83 | 0.6% |
| Randomized controlled trials | 138 | 0.9% |
Method: PubMed query "Siblings"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.
Reading the evidence in psychiatry and psychology
Research on mental health and behaviour relies on questionnaires, interviews and rating scales rather than physical measurements, so how a condition was defined and measured shapes every result. Many studies are observational or small, placebo responses can be large, and findings in one group or culture may not carry over to another. Nothing on this page is advice about diagnosis or treatment; anyone worried about their mental health should talk to a qualified clinician. Check how outcomes were measured, who took part and how long they were followed.
Evidence from open-access studies
These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.
| Study / authors | Year | Source label / design | Europe PMC citations | Licence / source |
|---|---|---|---|---|
| Generalizability and effect measure modification in sibling comparison studies | 2022 | Research article Design not recorded in structured metadata | 35 | cc by PMID 35312926 · DOI · PMC9209381 |
| Interpreting polygenic score effects in sibling analysis | 2024 | Research article Design not recorded in structured metadata | 28 | cc by PMID 38358994 · DOI · PMC10868763 |
| Mid-childhood autism sibling recurrence in infants with a family history of autism | 2024 | Research article Design not recorded in structured metadata | 18 | cc by PMID 38973707 · DOI · PMC11801122 |
| Investigating Parental Observations of Early Autism Development in Simplex and Multiplex Families | 2026 | Research article Design not recorded in structured metadata | 3 | cc by PMID 38642179 · DOI · PMC12987830 |
Generalizability and effect measure modification in sibling comparison studies [1]
Abstract reading summary — source excerpts
- Opening excerpt
- Sibling comparison studies have the attractive feature of being able to control for unmeasured confounding by factors that are shared within families.
- Closing excerpt
- Finally, we illustrate the theoretical conclusions with a simulation study.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (190 words)
Sibling comparison studies have the attractive feature of being able to control for unmeasured confounding by factors that are shared within families. However, there is sometimes a concern that these studies may have poor generalizability (external validity) due to the implicit restriction to families that are covariate-discordant, i.e., those families where at least two siblings have different levels of at least one of the covariates (exposure or confounders) under investigation. Even if this selection mechanism has been noted by many authors, previous accounts of the problem tend to be brief. The purpose of this paper is to provide a formal discussion of the implicit restriction to covariate-discordant families in sibling comparison studies. We discuss when and how this restriction may impair the generalizability of the study, and we show that a similar generalizability problem may in fact arise even when all families are covariate-discordant, e.g. even if the exposure is continuous so that all siblings have different exposure levels. We show how this problem can be solved by using a so-called marginal between-within model for estimation of marginal exposure effects. Finally, we illustrate the theoretical conclusions with a simulation study.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 35312926 · DOI · PMC9209381
Interpreting polygenic score effects in sibling analysis [2]
Abstract reading summary — source excerpts
- Opening excerpt
- Researchers often claim that sibling analysis can be used to separate causal genetic effects from the assortment of biases that contaminate most downstream genetic studies (e.
- Closing excerpt
- Our findings suggest that interpreting results from sibling analysis aimed at uncovering direct genetic effects should be treated with caution.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (174 words)
Researchers often claim that sibling analysis can be used to separate causal genetic effects from the assortment of biases that contaminate most downstream genetic studies (e.g. polygenic score predictors). Indeed, typical results from sibling analysis show large (>50%) attenuations in the associations between polygenic scores and phenotypes compared to non-sibling analysis, consistent with researchers' expectations about bias reduction. This paper explores these expectations by using family (quad) data and simulations that include indirect genetic effect processes and evaluates the ability of sibling analysis to uncover direct genetic effects of polygenic scores. We find that sibling analysis, in general, fail to uncover direct genetic effects; indeed, these models have both upward and downward biases that are difficult to sign in typical data. When genetic nurture effects exist, sibling analysis creates "measurement error" that attenuates associations between polygenic scores and phenotypes. As the correlation between direct and indirect effect changes, this bias can increase or decrease. Our findings suggest that interpreting results from sibling analysis aimed at uncovering direct genetic effects should be treated with caution.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38358994 · DOI · PMC10868763
Mid-childhood autism sibling recurrence in infants with a family history of autism [3]
Abstract reading summary — source excerpts
- Opening excerpt
- Autism sibling recurrence in prospective infant family history studies is ~20% at 3 years but systematic follow-up to mid-childhood is rare.
- Closing excerpt
- Findings have implications for families and clinical services, and for prospective family history studies.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (250 words)
Autism sibling recurrence in prospective infant family history studies is ~20% at 3 years but systematic follow-up to mid-childhood is rare. In population and clinical cohorts autism is not recognized in some children until school-age or later. One hundred and fifty-nine infants with an older sibling with autism underwent research diagnostic assessments at 3 years and mid-childhood (6 to 12 years (mean 9)). We report the autism sibling recurrence rate in mid-childhood and compare developmental and behavioral profiles at mid-childhood and 3 years in those with earlier versus later recognized autism, and those who had, or had not, received a community autism diagnosis. The autism recurrence rate in this sample in mid-childhood was 37.1%, 95% CI [29.9%, 44.9%] and higher in boys than girls. Around half of those diagnosed with autism in mid-childhood had not received a diagnosis at 3 years. Later, diagnosis was more common in girls than boys. While some had sub-threshold symptoms at 3, in others late diagnosis followed a largely typical early presentation. Sibling recurrence based on community clinical diagnosis was 24.5%, 95% CI [18.4%, 31.9%]. Those who also had a community diagnosis tended to be older, have lower adaptive function and higher autism and inattention symptoms. Notwithstanding limitations of a single site study, modest sample size and limits to generalisability, autism sibling recurrence in family history infants may be higher in mid-childhood than in studies reporting diagnostic outcome at 3 years. Findings have implications for families and clinical services, and for prospective family history studies.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38973707 · DOI · PMC11801122
Investigating Parental Observations of Early Autism Development in Simplex and Multiplex Families [4]
Abstract reading summary — source excerpts
- Opening excerpt
- Past research has highlighted the importance of early identification of developmental differences to improve targeted access to early interventions or supports.
- Closing excerpt
- These findings suggest that for children at elevated likelihood of autism, parents' concerns are driven primarily by developmental differences, with child's birth order and sibling diagnostic status not impacting on parent early concerns.
- Interpretation limits
- Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (189 words)
Past research has highlighted the importance of early identification of developmental differences to improve targeted access to early interventions or supports. As such, it is of particular importance in the context of children at elevated likelihood of autism (such as where an older sibling has a diagnosis of autism), to better understand when and which early concerns are important as predictors of which children will benefit from pre-diagnostic supports. This study explored the number and frequency of retrospective parent reported concerns within the first year of life for children diagnosed with autism, both those who had an older sibling diagnosed with autism and those who did not, as well as for undiagnosed siblings. We found that at both 0-6 and 7-12 months, the only factor related to the presence or absence of early parent reported concerns was child diagnostic status, with the presence of reported early concerns more likely for children with a diagnosis of autism. These findings suggest that for children at elevated likelihood of autism, parents' concerns are driven primarily by developmental differences, with child's birth order and sibling diagnostic status not impacting on parent early concerns.
Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 38642179 · DOI · PMC12987830
Key reviews and meta-analyses
The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.
- Research article Exposure to parental and sibling smoking and the risk of smoking uptake in childhood and adolescence: a systematic review and meta-analysis [5]
- Research article Psychosocial adjustment of siblings of children with cancer: a systematic review [6]
- Research article Siblings of children with a chronic illness: a meta-analysis [7]
- Research article Prospective Longitudinal Studies of Infant Siblings of Children With Autism: Lessons Learned and Future Directions [8]
- Research article Psychological functioning of siblings in families of children with chronic health conditions: a meta-analysis [9]
- Research article Psychosocial functioning and risk factors among siblings of children with cancer: An updated systematic review [10]
Full-text reviews on EvidenceLib
Open-access review articles about this topic, reproduced in full with authors, licence and references.
Early non-social behavioural indicators of autism spectrum disorder (ASD) in siblings at elevated likelihood for ASD: a systematic review
Daniela Canu, Sara Van der Paelt, Ricardo Canal-Bedia et al. · European Child & Adolescent Psychiatry 2021 · CC BY 4.0
References
- Sjölander A, Öberg S, Frisell T. Generalizability and effect measure modification in sibling comparison studies. . 2022. PMID 35312926 · DOI · PMC9209381
- Fletcher J, Wu Y, Li T, Lu Q. Interpreting polygenic score effects in sibling analysis. . 2024. PMID 38358994 · DOI · PMC10868763
- Bazelmans T, Arthur R, Pasco G, Shephard E, Milosavljevic B, Ali JB, et al.. Mid-childhood autism sibling recurrence in infants with a family history of autism. . 2024. PMID 38973707 · DOI · PMC11801122
- Cleary DB, Maybery MT, Waddington H, Macaskill E, Whitehouse AJO. Investigating Parental Observations of Early Autism Development in Simplex and Multiplex Families. . 2026. PMID 38642179 · DOI · PMC12987830
- Leonardi-Bee J, Jere ML, Britton J. Exposure to parental and sibling smoking and the risk of smoking uptake in childhood and adolescence: a systematic review and meta-analysis. Thorax. 2011. PMID 21325144 · DOI
- Alderfer MA, Long KA, Lown EA, Marsland AL, Ostrowski NL, Hock JM, et al.. Psychosocial adjustment of siblings of children with cancer: a systematic review. Psychooncology. 2010. PMID 19862680 · DOI
- Sharpe D, Rossiter L. Siblings of children with a chronic illness: a meta-analysis. J Pediatr Psychol. 2002. PMID 12403860 · DOI
- Szatmari P, Chawarska K, Dawson G, Georgiades S, Landa R, Lord C, et al.. Prospective Longitudinal Studies of Infant Siblings of Children With Autism: Lessons Learned and Future Directions. J Am Acad Child Adolesc Psychiatry. 2016. PMID 26903251 · DOI · PMC4871151
- Vermaes IP, van Susante AM, van Bakel HJ. Psychological functioning of siblings in families of children with chronic health conditions: a meta-analysis. J Pediatr Psychol. 2012. PMID 21994420 · DOI
- Long KA, Lehmann V, Gerhardt CA, Carpenter AL, Marsland AL, Alderfer MA. Psychosocial functioning and risk factors among siblings of children with cancer: An updated systematic review. Psychooncology. 2018. PMID 29441699 · DOI
About this article
- Sources
- NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
- Verification
- Every reference was resolved against PubMed on 2026-11-04; title, year and DOI matched.
- Review state
- automated source verified; no human expert review has been recorded yet.
- Version
- 1, last updated 2026-11-04.
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Evidence strength
EvidenceHelix's computed view of the study designs behind this topic: how common meta-analyses, randomized trials and reviews are, how recent the literature is, and a plain-language reading. It describes the design mix of the literature. It is not a quality appraisal of any study, and it is not medical advice.