Data are presented on the social backgrounds and IQs of a sample of scientists, their male sibs and their fathers. The range of IQ in the scientists is similar to the range of scores expected of the higher 25% of a representative general population sample.

The IQs of the scientists showed a positive correlation with social class. Differences in IQ between the scientists and their fathers in each social class are related to the distance the scientists have moved up the social scale. In the twenty-two families in which the IQs of the father and two male sibs are known the upwardly mobile sibs tend to have higher IQs than the non-mobile or downwardly mobile sibs.

In Class II there is evidence that stabilizing selection operates on IQ to maintain the mean IQ level. The effect on social stratification of such selection, together with increased educational opportunity, is discussed.

Earlier studies on psychotic patients suggested that their illegitimate fertility was lower than expected on the basis of general population trends. The present findings were part of a study on marriage and fertility of women suffering from schizophrenia and affective disorders since the impact of community orientated psychiatry; 1300 women were selected from admissions to a London hospital during 1955–63 and followed up until August 1966.

The proportion of total live births which were illegitimate was 19·1% among the schizophrenics, 7·5% among the affectives and 12·7% in the general population of London during 1961. The high illegitimate fertility of schizophrenics is probably related to their low probability of marriage; more births occurred before than after admission, especially among the older group of women suffering from affective disorders. Most of the births were the result of a serious relationship rather than casual promiscuity, and they were more frequent among Jamaican patients and patients with probable psychopathic personalities in both clinical groups. The genetic and social relevance of the study is discussed.

A semi-longitudinal study of factors influencing child growth in a rural community in Jamaica provided an opportunity to explore the relationships between diarrhoea, respiratory infections and body weight.

Respiratory infections and diarrhoea both reached peak incidences between the ages of 6 and 24 months when children are at highest risk of malnutrition. Respiratory infections had no demonstrable influence on growth. Diarrhoea was more common in boys than in girls and more common in underweight children. It had no influence on long-term weight increases, though it did have the expected influence on short-term increments.

The findings suggested that much of the diarrhoea seen in this community of children may have been secondary to undernutrition rather than a cause of it.

This paper describes the main findings of the first stage in a planned longitudinal study of marriage and family planning amongstarepresentative sample of recently married couples in a northern city. The long-term aim of the research is to evaluate, by means of interivews repeated at successive 5-year intervals in the lives of these couples, the relationship between intended and achieved family size and to assess the factors associated with relative success and failure. The initial series of interviews provides much new information on patterns of mate selection, marriage and family planning intentions; it also represents the only recent survey of contraceptive behaviour during the first year of marriage.

The major determinants of family-building behaviour are assessed and, amongst these, religion is found to be the most significant. Its effects are, however, mitigated by considerable marrying out amongst Catholics. The notion of the married couple as a rational decision-making unit in matters of family planning is supported by this survey and there is a rela tionship between desired family size and the efficacy of contraceptive usage. Two points of major methodological interest in fertility analysis are dis cussed.

Based on data obtained from the marriage registers of seven Oxfordshire parishes in the Otmoor region, an analysis has been made of the effects of social mobility and marriage exchanges on the relatedness of the five social classes which are recognized by the Registrar General. From a starting position in which it is assumed that there was no relatedness between the classes, it is calculated that under the average social mobility patterns which have characterized the area from 1837 to 1967 the different social classes would come to share 95% of their ancestry in sixteen generations. The marriage movement would produce the same levels of relatedness in twenty generations, and the combined effects of social mobility and marriage produce homogeneity in nine generations. It is further argued that these are maximal estimates but in considering the genetic implications it is noted that, whilst genes which do not affect social mobility and marriage movement are not likely to show social stratification in Otomoor populations, genes affecting behavioural traits may well be heterogeneously distributed.

The incidence of spina bifida and anencephaly, according to reports, has declined in some parts of the world but not in others. It is suggested that social factors, greater awareness of the familial nature of these disorders coupled with the increased availability of effective contraception, may account for part of the decline and that these factors are less operative in the areas where no decline in incidence has been observed.

Data are presented for 65 families living in the Manchester area, each of which contained at least one affected child. Forty of these families appeared to have been ‘discontinued’ after the birth of the affected child.