Rare diseases are usually complex syndromes, which sometimes cause extensive functional impairments affecting everyday life. The number of rare diseases and of people having one is increasing. Children with rare diseases often display special education needs and require support and adapted pedagogical methods to participate and achieve academic…

The lack of sex difference in left-handedness in Scandinavian countries reported by Papadatou-Pastou, Martin, Munafo, and Jones (2008) is questioned. We investigated the sex difference in left-handedness in two Finnish, one Norwegian, and one Swedish population-based sample not included in the Papadatou-Pastou et al. (2008) meta-analysis. The…

Standardized mathematics test results of a twin sample during grades 3 and 6 were interpreted according to an interactional heredity x environment model. Results indicated that similar school instruction made monozygotic twins more alike but dizygotic twins less alike in mathematics knowledge. Social background effects were also studied. (SJL)

Genetic effects on specific cognitive abilities as distinct from those on general cognitive ability were studied in 302 pairs of twins (some reared together, some apart) from the Swedish Adoption/Twin Study of Aging. Overall, results showed significant genetic influence on specific abilities independent of influence on general ability. (SLD)

The role of biological maturity in behaviors in adolescents which most often are considered as negative by adults was investigated for a normal group of girls. (Author/LMO)

The consciousness of dizygotic twins in their communication of actions and events as seen in the visual cliff pictures published by E. J. Gibson and R. D. Walk (1960) was studied in Sweden. In the process of communication, many different state spaces are generated. The methodology demonstrates that ecological and biophysical properties of language…

Biosocial influences on sex differences, found for school achievement test results in grades 3 and 6, have been studied by means of opposite-sex twin pairs and singleton controls, attending the same classes as the twins. As expected the opposite-sex twin pairs tend to be more similar in achievement test results in Swedish and mathematics than…

Investigated long-term effects of infant temperament on problem behavior and cognitive abilities at age 5 years, taking into account interactions between infant temperament and biological and social risk. Found that when high scores on temperamental factors are combined with social or biological risk, the level of later behavioral problems is…

The relationship between biological maturation, as evidenced by skeletal growth, during adolescence and the development of drinking habits and alcohol abuse was studied for a representative group of Swedish males (N=88). Early and late maturers had more advanced drinking habits at age 14 years than did normally maturing subjects. (TJH)