An attempt was made to predict alcohol use among 101 American white boys aged 13–16. The model combined genetic and social variables. The analysis revealed evidence of a genotype–environment interaction and thus the use of either the biological or social variables alone poorly predicts alcohol use.

Levels and trends of fertility in the Arsi and Shoa regions of Central Ethiopia are examined, using data from the 1986 Population, Health and Nutrition baseline survey of the Ministry of Health of Ethiopia. The population has high fertility. Total fertility of six children per woman in the late 1960s increased to eight children per woman in the early 1980s, then declined to seven children per woman in the mid-1980s. Urban fertility declined by a substantial amount during the 15 years before the survey while rural fertility increased during the same period.

The implications of high fertility are considered.

Analyses of the height variation of 16-year-old members of the British National Child Development Study revealed a number of biological and social variables which associated with stature. After multiple regression analyses only eight variables, namely social class, family size, tenure (owner occupied or one of several types of rented home), crowding status, number of children sleeping in the bed, region of the country, sex of child, and pubic hair rating, remained significant. The total variation explained by these biosocial variables was 37·5%.

Japanese and British 9-year-old children were compared on the standard progressive matrices and twelve reaction time parameters providing measures of simple and complex decision times, movement times and variabilities. The mean of the Japanese children on the progressive matrices exceeded that of the British children by 0·65 SD units and on the decision times component of reaction times by 0·50 SD units, suggesting that the high Japanese mean on psychometric intelligence is largely explicable in terms of the more efficient processing of information at the neurological level. Japanese children also showed faster movement times but, contrary to expectation, had greater variabilities than British children.

Social and biological factors influencing birthweight of 3053 Ilorin babies were studied. The mean birth weights were 2·998 kg ±0·133 (SD) for males and 2·932 kg ± 0.154 (SD) for females. Multiple regression analysis showed that maternal weight, height, age, education and ethnicity, and child's sex, significantly affected birthweight of infants. Some quadratic and interaction terms also contributed significantly to the prediction of birthweight. The strategies to control the incidence of low birth weight are discussed.

The Nepal Fertility and Family Planning Survey of 1986 demonstrated that demographic variables, previous birth interval and survival of preceding child, still predominated as determinants of infant mortality, particularly in rural areas of Nepal. However, in urban Nepal, where the level of socioeconomic development is higher, an environmental variable, along with previous birth interval and survival of preceding child emerges as important in determining infant mortality. Separate policy measures for child survival prospects in rural and urban Nepal are suggested.

Infant and child mortality differentials are analysed by education of parents and other family members, access to toilet, electricity and source of drinking water in urban Nepal, using data from the Nepal Fertility and Family Planning Survey, 1986. The analyses showed significant effects of education, access to toilet and electricity in lowering infant and child mortality. Access to toilet and electricity are proxies for house-hold socioeconomic status which suggests that education and household resources are complementary in lowering the infant and child mortality.

Data from an historical population in which fertility control was minimal and modern health services were mostly unavailable are used to show that there appears to have been a strong association between previous birth interval length and infant mortality, especially when the previous child survived. Although only imperfect proxies for breast-feeding practices and other potentially confounding factors are available for this population, the results suggest that the association between previous interval length and infant mortality in this population is not solely, or primarily, a function of differences in breast-feeding behaviour or socioeconomic status. Other factors, e.g. maternal depletion or sibling competition, are more likely to explain the observed association.

A 1980–81 survey of the rural population of Ethiopia found high levels of infecundity and subfertility, although there was considerable variation by region, ethnicity and age of women. Higher levels of infecundity were geographically concentrated in a broad belt that ran from the south and south-west of the country, across to the north-east. The analyses suggest that infecundity is influenced by ecological factors, more than by ethnicity.

Information on levels, trends and determinants of infant and child mortality was available from the 1985 In-depth Fertility Survey which was conducted in three provinces of China. Mortality of children below age 5 varied from 49 per 1000 live births in Shaanxi to 20 in Shanghai in 1980–85 and has declined substantially since 1960, from 206 in Shaanxi and 66 in Shanghai. Male mortality was considerably higher than female mortality in the neonatal and post-neonatal period, and at ages 1–5 years. Birth weight, place of residence and mother's education were found to be important determinants of mortality; age of mother and parity were less important.

A longitudinal sample of 21-year-old Australians from Anglo-Australian, Greek and Southern Italian families was used to examine relationships of children's cognitive performance, family learning environments, adolescents' perceptions of family learning contexts, and measures of young adults' social status attainment. Generally, the findings using a regression approach indicated that there were ethnic group differences in the relations between parents' academic socialisation, children's cognitive performance, and measures of young adults' social status attainment. The results also showed that in each ethnic group, adolescents' perceptions of parents' support for learning had strong associations with young adults' status attainment.

A survey of 232 households of the Mosuo minority group in Yunnan Province, People's Republic of China, suggested that polyandrous matriarchy did not raise the birth rate per household, but lowered the community birth rate by restricting many women's chances of marrying. The results imply that tolerance by the national government of polyandry within certain minority groups (e.g. Mosuos and Tibetans) will not prevent but may aid the attainment of zero population growth by China in the twenty-first century.