This study aimed to identify linear growth trajectories from 0-5 years and assess their associations with cognitive function and school achievement in Ethiopian children aged 10 years. Latent class trajectory modelling was used to identify distinct height-for-age (HAZ) trajectories. Cognitive function was assessed using the Peabody Picture Vocabulary Test (PPVT), while school achievement was measured by Math, English, and Science (MES) combined scores and grade-for-age. Associations were assessed using multiple linear or logistic regressions.

We identified 4 distinct HAZ trajectories. Decreasing trajectory (n=145, 31.9%) started high at birth but dropped sharply. The increasing-decreasing trajectory (n=196, 43.2%) increased up to 3 months followed by a decrease. The stable low (n=74, 16.3%) had low HAZ at birth, followed by a slight decrease. The rising trajectory (n=39, 8.6%) started low but then increased to HAZ above, yet close to zero. At 10 years, children in the rising trajectory had 4.54 (95% CI: -0.45, 9.55, p=0.075) higher MES combined score and 2.4 times (95% CI: 1.12, 5.15, p=0.025) higher odds of being in the appropriate grade-for-age compared to those in the increasing-decreasing trajectory. The association between stable low and decreasing trajectory with appropriate grade-for-age had odds ratio close to null.

In conclusion, we found that three of the four linear growth trajectory classes showed a declining pattern. Data suggest that greater linear growth in early childhood may be associated with higher school achievement and better cognitive function.

School engagement has been shown to be a strong predictor for school achievement. Previous studies have focused on the role of individual and contextual factors to explain school achievement, with few examining the role of siblings. This study used data of 451 adolescent sibling pairs from the Iowa Youth and Families Project to investigate the associations between school engagement and achievement in siblings by considering gender composition and birth order. Data were collected in families’ home and obtained for a target child in the 7th grade and for a sibling within 4 years of age. Average age of younger siblings (55% female) was 11.56 (SD = 1.27), while older siblings (49% female) had an average age of 13.92 (SD = 1.47). Using the two-member, four-group actor-partner interdependence model (APIM), results showed that older siblings’ engagement was positively related with younger siblings’ achievement in same-gender sibling pairs, but not in sibling pairs of opposite gender. Younger siblings’ engagement was independent of older siblings’ achievement regardless of siblings’ gender. Implications for parents and professionals suggest that support for older siblings could also benefit younger siblings in same gender pairs.

The relations of Gf (Standard Progressive Matrices Raven), Gc (verbal scale of Wechsler Intelligence Scale for Children-Third Version), personality dimensions (Eysenck Personality Questionnaire-Junior Version), and disruptive behavior (TDAH scale) with school achievement (measured by TDE test and PISA test) were investigated. Two samples of students (total N = 534) representing a broad range of socioeconomic status (SES) participated in this study. Path models were conducted. The results demonstrated that (1) in both samples no sex differences related to school achievement were found; (2) in the first sample, after controlling for age and SES differences, Gf and psychoticism predicted (.38 and −.13, respectively) school achievement (measured by TDE test); (3) in the second sample, after controlling for SES differences to which additional measures were administered, Gf and Gc positively predicted (.22 and .40, respectively) school achievement (measured by PISA test). In addition, psychoticism and disruptive behavior also predicted school performance (−.14 and −.28, respectively). Some theoretical and practical implications are discussed.

The Russian School Twin Registry (RSTR) was established in 2012, supported by a grant from the Government of the Russian Federation. The main aim of the registry is to contribute to Progress in Education through Gene-Environment Studies (PROGRESS). The formation of the registry is ongoing and it is expected that most schools in the Russian Federation (approximately 50,000 schools) will contribute data to the registry. With a total of 13.7 million students in Grades 1–11 (ages 7–18), the potential number of twin pairs exceeds 100,000. Apart from the large sample size and its representative nature, the RSTR has one unique feature: in collaboration with the International Advisory Committee to the Registry, genetically sensitive cross-cultural investigations are planned, aided by the use of the common assessment instruments. Other strengths of the registry include the assessment of a large sample of non-twin school children, including those studying in the same classes as the twins in the registry. It is hoped that the RSTR will provide an important research platform for national and international educationally relevant research.

This article summarizes the status of three recent German twin studies: CoSMoS, SOEP, and ChronoS. The German twin study on Cognitive Ability, Self-Reported Motivation, and School Achievement (CoSMoS) is a three-wave longitudinal study of monozygotic and dizygotic twins reared together, and aims to investigate predictors of and influences on school performance. In the first wave of the data collection in 2005, 408 pairs of twins aged between 7 and 11 as well as their parents participated in CoSMoS. The SOEP twin study is an extended twin study, which has combined data from monozygotic and dizygotic twins reared together with additional data from full sibling pairs, mother–child, and grandparent–child dyads who participated in the German Socio-Economic Panel (GSOEP) study. The SOEP twin project comprises about 350 twin and 950 non-twin pairs aged between 17 and 70. Data were collected between 2009 and 2010, with a focus on personality traits, wellbeing, education, employment, income, living situation, life-satisfaction, and several attitudes. The aim of the Chronotype twin study (ChronoS) was to examine genetic and environmental influences on chronotype (morningness and eveningness), coping strategies, and several aspects of the previous SOEP twin project in a sample of 301 twin pairs aged between 19 and 76 years, recruited in 2010 and 2011. Part of the ChronoS twin sample also participated in the earlier SOEP twin study, representing a second wave of assessments. We briefly describe the design and contents of these three studies as well as selected recent findings.

Using longitudinal cross-lagged analysis to infer causal directions of reciprocal effects is one of the most important tools in the developmental armamentarium. The strength of these analyses can be enhanced by analyzing the genetic and environmental aetiology underlying cross-lagged relationships, for which we present a novel approach here. Our approach is based on standard Cholesky decomposition. Standardized path coefficients are employed to assess genetic and environmental contributions to cross-lagged associations. We indicate how our model differs importantly from another approach that does not in fact analyze genetic and environmental contributions to cross-lagged associations. As an illustration, we apply our approach to the analysis of the cross-lagged relationships between self-perceived abilities and school achievement from age 9 to age 12. Self-perceived abilities of 3852 pairs of twins from the UK Twins Early Development Study were assessed using a self-report scale. School achievement was assessed by teachers based on UK National Curriculum criteria. The key cross-lagged association between self-perceived abilities at age 9 and school achievement at age 12 was mediated by genetic influences (28%) as well as shared (55%) and non-shared (16%) environment. The reverse cross-lagged association from school achievement at 9 to self-perceived abilities at 12 was primarily genetically mediated (73%). Unlike the approach to cross-lagged genetic analysis used in recent research, our approach assesses genetic and environmental contributions to cross-lagged associations per se. We discuss implications of finding that genetic factors contribute to the cross-lag between self-perceived abilities at age 9 and school achievement at age 12.

The results presented in this paper are part of a current comparative study of genetic and environmental influences in three educational settings: Stockholm, Jerusalem and the Israeli kibbutz. We specifically wanted to investigate whether a more restrictive educational setting would decrease genetic influences. Here we report on comparisons of cognitive performance measures at several time points for twins/controls, boys/girls and within-pair similarity in MZ, DZ and controls. The tests used were the Raven Progressive Matrices, verbal, reading comprehension and arithmetic. The results show no differences between twins and controls, whilst gender differences seem to be smallest in the Stockholm sample and largest in Jerusalem. A pattern of genetic influences on cognitive performance was also clearly visible in Jerusalem. In Stockholm shared environmental influences at home and at school seemed even stronger than in the kibbutz. No consistent differences were found between tests or occasions.

The aim of the present study was to examine the association between maternal Hb levels during pregnancy and educational achievement of the offspring in later life. We analysed data obtained from the Northern Finnish Birth Cohort Study conducted in 1966, in which, data on mothers and offspring from pregnancy through to the age of 31 years were collected. The cohort comprised 11 656 individuals born from singleton births (51 % males and 49 % females). Maternal Hb levels were available from the third, seventh and ninth gestational months. Educational achievement was measured as school scores (range 4–10) taken at the ages of 14 (self-reported questionnaires) and 16 (school reports) years as well as the highest level of education at the age of 31 years. The present results showed a direct positive association between Hb levels and educational achievement in later life. After adjustment for sex, birth weight, birth month and a wide range of maternal factors (parity, smoking, mental status, whether pregnancy was wanted or not, education, social class and marital status), only maternal Hb levels that were measured at the ninth month were significantly associated with the offspring's school performance. If the levels were ≥ 110 g/l at all the three measurement points, offspring not only had better school scores at the ages of 14 and 16 years (β = 0·048, P = 0·04 and β = 0·68, P = 0·007, respectively), but also had an increased odds of having a higher level of education at the age of 31 years (OR = 1·14, P = 0·04). The present study suggests that low maternal Hb levels at the final stages of pregnancy are linked to the poorer educational achievement of the offspring. If our observation is confirmed, it would suggest that Fe prophylaxis even at fairly late stages of pregnancy may be beneficial for the subsequent health of the offspring. However, more studies are needed to fully establish the potential pathways and the clinical importance of the present findings.

An estimated 1049 million persons harbour T. trichiura, including 114 million preschool-age children and 233 million school-age children. The prevalence of T. trichiura is high and may reach 95% in children in many parts of the world where protein energy malnutrition and anaemias are also prevalent and access to medical care and educational opportunities is often limited. The Trichuris dysentery syndrome (TDS) associated with heavy T. trichiura, which includes chronic dysentery, rectal prolapse, anaemia, poor growth, and clubbing of the fingers constitutes an important public health problem, as do lighter but still heavy infections, even if not strictly TDS, especially in children. The profound growth stunting in TDS can be reversed by repeated treatment for the infection and, initially, oral iron. However findings from Jamaica strongly suggest that the significant developmental and cognitive deficits seen are unlikely to disappear without increasing the positive psychological stimulation in the child's environment. The severe stunting in TDS now appears likely to be a reaction at least in part to a chronic inflammatory response and concomitant decreases in plasma insulin-like growth factor-1 (IGF-1), increases in tumor necrosis factor-α (TNF-α) in the lamina propria of the colonic mucosa and peripheral blood (which likely decrease appetite and intake of all nutrients) and a decrease in collagen synthesis. Improvements in cognitive performance have been found after treatment for relatively heavy infections (without chronic dysentery) in school-going children; it is unclear precisely how much T. trichiura interferes with children's ability to access educational opportunities, but treatment of infections whenever possible is obviously sensible. The blood loss that can occur in T. trichiura infection is likely to contribute to anaemia, particularly if the child also harbours hookworm, malaria and/or has a low intake of dietary iron. Community control is important, particularly for the individuals within a population who harbour heavy worm burdens; this means children, with special attention to girls who will experience increased iron requirements and blood loss due to menstruation, pregnancies, and lactation. Mebendazole and albendazole, both of which are on the WHO Essential Drugs List, are very effective against T. trichiura; multiple doses are needed to attain complete parasitological cure in all cases. However the goal of control programmes in endemic areas is morbidity reduction, which follows when intensity of infection is significantly reduced.

Associations between the extent of conduct problems at age 8 years and later life opportunity outcomes at age 18 years were examined in a birth cohort of New Zealand children studied prospectively to age 18 years. Conduct problems at age 8 were assessed using a combination of parent and teacher reports of conduct disordered and oppositional behaviours. Two measures of life opportunities were assessed at age 18: (a) whether the young person had left school by age 18 without educational qualifications; (b) whether the young person had experienced a period of unemployment of 3 months or longer following school leaving. The analysis suggested the following conclusions: (1) There were clear and significant (p<.0001) tendencies for increasing levels of conduct problems at age 8 to be associated with increasing risks of leaving school without qualifications and of unemployment by age 18. (2) A substantial component of these associations was explained by a series of confounding social, family, and individual factors (notably child intelligence, early attentional problems, and family sociodemographic disadvantage) that were associated with both early conduct problems and later life opportunities. (3) Further analysis suggested that linkages between early conduct problems and later educational underattainment and unemployment (after adjustment for confounders) were mediated by a series of adolescent behavioural processes including patterns of peer affiliations, substance use, truancy, and problems with school authority.

In a previous Swedish twin project (the SLU-project), approximately 300 MZ and DZ twin pairs and controls were followed through the Swedish compulsory school from grade 3 to grade 9. Results from this study indicated an increase of genetic influences on school achievement over time for children from a permissive home environment and a decrease for children from a restrictive home environment. These types of data have generated a more general model for studying heredity-environment interaction in educational settings. To test this model, a cross-cultural comparison over time of twins and controls in the Israeli kibbutz school and in the Swedish compulsory school has been made. Restrictions on the child were originally assumed to be more apparent in the kibbutz environment.

In a follow-up study of 234 twin pairs, now aged 12-20 yrs, the intertwin relationships were evaluated by the parents and the twins themselves. The dominance-submissiveness aspect was inquired from three separate points of view, physical dominance, psychic dominance, and role of the spokesman. These three different aspects of dominance reflected on the twins' well being and mental health in somewhat different ways. The submissiveness in one area was often compensated by equality or dominance in another area, with only about 10% of adolescents being submissive or dominant in all three areas. According to the parents' reports, the most submissive twins suffered most often from psychosomatic symptoms, and the most dominant ones from nervous symptoms. The twins who themselves reported to be most submissive had most often somatic complaints and scored highest in the Kovacs' Depression Inventory.

In 1975 the Australian Council of Educational Research (ACER) conducted a nationwide survey of literacy and numeracy in 10- to 14-year olds. A total of 297 of the 12875 children involved were twins. By age 14, only 42% of the twin boys achieved adequate standards of literacy compared with 71% of single-born boys. The deficit in twin girls was much less and twins of both sexes were only moderately behind in numeracy. A survey of 9-13-year-old twin boys in the La Trobe Twin Study (LTS) produced similar results with 75% being below average in reading skills and 23% behind by 18 months or more, despite above average IQs. The ACER data are corroborated by teachers' reports obtained in the same survey, which indicate also how few of the twins with problems are receiving remediation and the high incidence of classroom problems in spelling and reading reversals. The pattern of mistakes twins make on specific items in the ACER survey can be explained as resulting either from specific cognitive deficits or from problems in concentration. The same factors influence performance on different tasks, so that literacy and numeracy are much more closely interrelated in twins than in singletons, and also correlate more with a measure of verbal intelligence. Implications for genetic analysis of scholastic achievement are examined, centering around the different factor structure of abilities in twins and common family environmental effects which are unique to twins.