Here’s a strange thing: the majority of families in the United Kingdom have more than one child, yet we know relatively little about whether having a sibling helps or hinders our students’ school experience.

It’s strange because, anecdotally, it would seem to have a significant impact. When a sibling is about to join a school where their older sibling is already in attendance, we naturally make assumptions about the new student based on our knowledge of their brother or sister, though we do our best to banish these thoughts.

Likewise, we attempt to rid ourselves of the urge to compare one sibling against another, but the tendency can sneak back in. And the younger sibling will always have the advantage (or disadvantage) of not being a total unknown to the school because the older sibling has meant connections with a family are already in place.

What do we know?

There are several intriguing stereotypes about siblings that we can all fall for: the domineering older sibling, the aimless middle child or the dependent youngest sibling, doted on by parents.

If you have a genius older sister, perhaps that makes you shrink in school. But it may just as well drive you on to better things. If you have a sporty older brother who is out to squash your academic interests at every chance they get, perhaps the effects will prove damaging for your dreams of school success. Conversely, they could drive you onto greatness.

We just don’t know for sure how all these things may combine or whether they have any impact at all. We are heavy on anecdote, but thin on facts.

The bulk of the evidence on families indicates that having more children in a family dilutes the available resources and proves damaging for children’s educational opportunities, with children from larger families having lower levels of education on average. Bigger really isn’t better, it appears.

But when you explore some of the more reputable research evidence, you realise that having siblings can indeed help, at school and beyond. Big brother, it turns out, is watching and helping you.

Back in 2014, Dr Birgitta Rabe and Professor Cheti Nicoletti, from the Institute for Social and Economic Research at the University of Essex, explored the “sibling spillover effect” (bit.ly/SiblingResearch). Having looked at siblings’ key stage 2 test results compared to their GCSE scores (between 2007 and 2010), they found that having an older sibling had a positive effect on school outcomes, especially for children from disadvantaged backgrounds.

The research by Nicoletti and Rabe indicates that “for each exam grade improvement of the older sibling - for example from a B to an A - the younger sibling’s exam marks increase by 4 per cent on average, which is equivalent to the impact of increasing yearly per pupil school expenditure in the younger sibling’s school by £670.”

Not only that, when the siblings are at the same school, the impact doubles. These benefits increase still further for children from disadvantaged families.

Why having an older sibling helps boost school attainment is open for debate. We can guess that simply sharing the daily experience of school with your older brother or sister may positively compensate for the lack of parental information in some families.

From choosing the right qualifications to knowing the nuances of homework and how to get by, having a big brother or sister watching over you really could have great benefits.

How many schools have considered the role of siblings? In all my years of teaching, I have never thought hard about it.

We take for granted that the life of a school has a near-hidden academic language. For the parents who dutifully attend each parents’ evening and communicate regularly with school, it becomes a code they learn. But for many parents (some from immigrant families whose grasp of language proves a further barrier), the language of school distances them and their child may consequently suffer. Indeed, Nicoletti and Rabe show that “the spillover effect is almost double among siblings not speaking English at home, compared to native English.”

My personal sibling school experience was a beneficial one. My eldest sister was the first person in my family to ever attend university. Although I didn’t know it then, it made the hope of dreaming spires something tangible, not just the stuff of the fiction I had read.

My older brother...well, he could euphemistically be described as not the school type. Still, his reputation and stature (a hulking 6ft 5in) meant I felt safe when I arrived as a 10-stone weakling at my all-boys secondary school.

Although being one of four children had its disadvantages, it bolstered my school experience in ways I did not appreciate back then. There are obvious ways, like my sister cooking my dinner when my parents both were both at work, and the implicit emotional support through the travails of typical school life: the friendships, the fights and the insider knowledge about teachers and their foibles.

We know that many middle-class parents manage to support their children with “concerted cultivation” - that is, they guide their qualification choices, help with homework and provide the money and materials needed for school success. But many other parents - particularly those from working-class families - may provide important support but lack the insider knowledge to engineer academic success. They will assume their child will simply “get on”. Here, the sibling spillover clearly helps.

What should schools do?

Great teachers and school leaders invariably do the simple things well. They “notice”. Beyond the acres of Excel spreadsheets and data mountains, we need to notice some of the subtle indicators that can determine school success for our students. From isolation at lunchtime to learning barriers in the classroom, we can better notice and support our students - like a big brother or sister would.

We know each child requires our support, but some children have additional barriers in school. Success, of course, not only encompasses academic gains, but also our students developing friendships and thriving happily. From free school meals and English as an additional language to pupil premium, beneath the well-known labels lies a wealth of knowledge about our students and their families. We should be more explicit in foregrounding siblings in that equation.

We should ask: how can we support this further and nudge it to happen in positive ways? Do parents of students with multiple siblings need fewer communications, freeing us to support parents of first-timers?

And what about those children who don’t have a sibling to support them? Schools can prove vast and intimidating places for such children. Many schools already have existing mentor or similar whole school support systems that make schools feel that little bit more personal, like supportive families do.

Ultimately, we should aim to cultivate a culture where kindness spills over, with every student standing up to act like a caring big brother or sister.

Alex Quigley is director of Huntington Research School in York. He is the author of The Confident Teacher, published by Routledge

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