How influential is preschool on a student’s school performance? Does a public or private school guarantee better student success? What bearing do sleep, diet and technology use have on grades? And how do a student’s genes interact with these and other factors thought to be important in academic standing and growth?
A ground-breaking, decade-long UNE project exploring the school achievements of twins and triplets has been helping us find answers to these and other questions.
The longitudinal Academic Development Study of Australian Twins (ADSAT) is the first project of its kind in Australia and has amassed revealing data on 2,762 twin pairs, 40 triplet sets and 1,485 non-twin siblings. Using the National Assessment Program: Literacy and Numeracy (NAPLAN), and regular parent surveys, it has given researchers a unique picture of the behaviours and demography that contribute to educational achievement – and the extent to which our genes influence them.
Dr William Coventry with his own twin, Charles Coventry, age 40.
The study has been directed for the past 10 years by Dr William Coventry and Professor Brian Byrne, who were joined in 2012 by then PhD student Dr Katrina Grasby, and project manager Dr Sally Larsen. In 2017 the study team also welcomed postdoctoral fellow Dr Callie Little for three years.
Twins are wonderful study subjects for a number of reasons. Their genetic similarity enables researchers to explore the degree to which a person’s genetic makeup (“nature”) influences certain outcomes, contrasted with environmental factors (“nurture”). This is done by comparing how similar identical twins are (who essentially share all the same genes) with how similar non-identical twins are (who only share on average half their genes).
In addition, twinsgrowing up in the same household, as all those in the UNE project are, share important aspects of their environments, such as family wealth, parents’ attitudes to education, access to books and computers, and so on, allowing researchers to estimate the influence of those shared environments after genetics has been taken into account.
Types of data collected
The UNE research team has gathered detailed information on twins’ health, preschool attendance, sleep, diet, participation in extra-curricular activities, technology use and homework behaviour, along with NAPLAN results in grades 3, 5, 7 and 9.
“A database of this size and scope provides a wealth of opportunities to explore features specific to Australian schooling and predictors of academic achievement,” said ADSAT data manager Dr Sally Larsen.
The broad, comparative data we have collated and our key findings can contribute to important discussions around how to ensure the best outcomes for all Australian school students.
“We can’t understand influences on development unless we do longitudinal research and look at how students are progressing over time. The fact that we have followed the twins and triplets across four rounds of NAPLAN testing is another strength of our project.
“There are opportunities for a range of investigations to answer strictly scientific questions about the extent to which genetic differences between people contribute to differences in academic results, and other behavioural characteristics. ADSAT has given us the opportunity to test some of the long-held, previously accepted assumptions about students’ achievement at school.”
ADSAT Results
Among the major ADSAT findings to date are that:
- Genetic differences among students are the single biggest influence on differences in literacy and numeracy standing and growth, accounting for half or more of that variability across tests and across time.
- The home environment that twins share has an unexpectedly modest influence on NAPLAN results after genes have been taken into account. Most of the non-genetic (environmental) influence is due to factors that are unique to members of twin pairs, such as individual friends or health conditions, with many of these factors as yet unidentified.
- Identical twins learning in different classrooms with different teachers perform almost as similarly in literacy and numeracy as pairs sharing the same classroom and teacher, indicating that the influence of individual teachers may have been overestimated.
- Contrary to widely held beliefs, preschool attendance is not associated with subsequent higher academic achievement in NAPLAN tests. The children who did not attend preschool were not behind in NAPLAN across the test years, and for those that did attend, variation in the total time of preschool attendance was not a factor either.
- Students attending private schools make no more progress in literacy and numeracy from Year 3 to Year 9 than students attending public schools.
“We hope our findings can inform educational policy-makers looking to design and deliver interventions that can help struggling children to reach their potential. As one example, we have suggested that any financial assistance available to students struggling with reading development be directed to individual students rather than to the school or even classroom.
For future researchers, this large dataset offers all kinds of possibilities for study, as well as training the next generation of quantitative researchers in education and behavioural genetics.
The ADSAT team will continue to follow up existing cohorts of twins until they finish Year 9 next year. Funding permitting, it would like to continue tracking the academic success of study participants beyond secondary schooling and into early adult life.
