Consanguineous marriage in the capital city Sana'a, Yemen

Consanguineous marriage is traditionally common throughout the Eastern Mediterranean region, especially in the mainly Muslim countries. To date, there is little information on consanguinity in Yemen. The aim of this study was to ascertain the rate of consanguineous marriage and average coefficient of inbreeding in Sana'a City, Yemen. A population survey was conducted with the intention of covering married couples resident in Sana'a City by means of a multi-stage random sampling technique. A total of 1050 wives and husbands were interviewed on consanguinity in their households. The total incidence of consanguinity was 44-7% (95% CI 41.7-47.7%) with first-cousin marriages constituting 71.6% of the total consanguineous marriages and 32% of all marriages. Paternal parallel first cousins (Type I) accounted for 49% of first-cousin marriages. The average coefficient of inbreeding (F) was 0.02442. The incidence of consanguinity is relatively high in Yemen with predominantly first-cousin marriage. This might be related to the deeply rooted social and cultural beliefs in the country.     

Frequency of first-cousin marriages from civil marriage certificates in Argentina

In Argentina information concerning relatedness of mates, especially first cousins, was introduced into the legal marriage certificate, record, and statistical report in 1968. The 1980-1981 biennial data, including 212,320 legal marriage reports, were analyzed for all of Argentina, subdivided into 22 states and 494 counties. The registered 0.373% of first-cousin marriages allows an estimate of consanguineous marriages of 0.629% and a mean inbreeding coefficient of alpha = 0.00031. This estimate lies between the observed alpha = 0.00011 from hospital births and alpha = 0.00052 from Roman Catholic Church dispensations. These differences are not large, and they may be due to sampling variations, indicating a low rate of inbreeding in Argentina. The frequency of first-cousin marriages in the 22 Argentine states is heterogenous, and 9 counties, representing 5 different regions, were identified as having a high rate of first-cousin marriage. Three of these were previously known as genetic isolates. A second series of data, including all 32,690 legal marriages registered in the state of Buenos Aires during the first half of 1984, showed a frequency of first-cousin marriages of 0.677%. First-cousin mates, compared with non-first-cousin mates, had a higher frequency of both mates being born in the same state of Buenos Aires and similar frequency distributions for age at marriage, single previous marriage status, level of education, and rate of unemployment. It is concluded that legal marriage data on consanguinity is reliable, inexpensive, universal, and enduring. The last two characteristics make them suitable for the survey of geographic clusters and time trends.     

Consanguinity in Spain: socioeconomic,demographic, and geographic influences

Information on consanguinity in Spain was reanalyzed in order to obtain a more complete picture of consanguinity patterns by considering temporal, geographical, demographic, and economic factors. To obtain data on consanguineous marriages, we reviewed 106 published references. Only populations with homogeneous geographical characteristics, economic activities, transportation facilities, and the like, were considered. Two-way analysis of variance (ANOVA) provided highly significant differences (p < 0.001) for a both for time periods and for urban versus rural patterns, but there was no interaction between the latter two. A regression analysis shows that for rural areas the geographic characteristics, economy, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient. The results obtained indicate that urban and rural patterns differ significantly and that the temporal factor needs to be taken into account before comparing inbreeding coefficients. In urban areas the census size and altitude are included in the regression equation as significant variables, but association was not found between alpha and the index of demographic tendency (population increase or decrease). Instead, the absolute number of inhabitants (census size) was significant. In rural areas geographic characteristics, communications, and index of demographic tendency were significant predictors of the inbreeding coefficient.     

Prevalence and sociodemographic correlates of consanguineous marriages in Turkey

The aim of this study was to determine the prevalence and sociodemographic correlates of consanguineous marriages in Turkey using data derived from the 2003 Turkey Demographic and Health Survey (TDHS-2003). Demographic surveys conducted in the last 40 years consistently show that Turkey is a country with a high level of consanguinity. In the latest demographic survey (TDHS-2003), a nationally representative sample of 8075 ever-married women, consanguineous marriages accounted for 22% of the total, which is equivalent to a mean coefficient of inbreeding (alpha) of 0.011. There are changing secular profiles in the rates of consanguinity in general and of the specific sub-types of cousin marriages in particular in Turkey. The prevalence of first cousin marriages among all consanguineous marriages presents a steady decline from one marriage cohort to the next. The changes observed over time may be attributable to several factors such as the increase in educational level of women, the nuclearization of the family system, the mobility from rural to urban settings, a better socioeconomic status of families, an increase in women's labour force participation in formal sectors, lower fertility rates resulting in a smaller number of cousins available for marriage, and an increased awareness of the effects of consanguineous unions on child health in cases where there is an inherited recessive disease in the family. Any attempts to discourage consanguinity at the population level appear to be inappropriate and undesirable, especially when the consanguineous union remains an integral part of the cultural and social life of Turkey. Nevertheless the WHO-recommended approach to minimizing the negative effects of consanguinity on child health should be followed, i.e. the identification of families with a high risk of a genetic disease and the provision of prospective genetic counselling.     

The prevalence and correlates of consanguineous marriages in Yemen: similarities and contrasts with other Arab countries

Using data on 9762 women from the 1997 Yemen Demographic and Maternal and Child Health Survey, this paper examines the prevalence and socioeconomic correlates of consanguineous marriages in Yemen. The results indicate that 40% of marriages are consanguineous, over 85% of which are between first cousins. The prevalence of consanguineous marriages appears to have increased over time, particularly for the last marriage cohort. As for socioeconomic correlates, the study confirms the inverse association between consanguineous marriages and women's education and occupation, age at marriage and economic status. However, no statistically significant difference in the prevalence of consanguinity has been found by place of residence and geographical region. Somewhat unexpected results have been obtained by husband's background characteristics, with higher educated men and those working in the modern sector of the economy being more likely to be married to cousins.     

Geographic, demographic and inbreeding patterns in a Basque mountainous region of Guipuzcoa

The Goierri, a mountain region within the Basque Hills of Guipúzcoa, includes one of the most culturally controlled autochthonous populations within the Basque area, mainly from linguistic point of view. The effects of geography and demographic changes (1862–1995) on consanguinity variables over its 21 Municipalities have been investigated. Rates of consanguineous marriages and mean inbreeding levels recorded in some of the southern villages can be considered high but, average values for the entire region were lowered due to the early industrialization of the province. In spite of that, consanguinity in the study area has been, for a long time, a prevailing and conspicuous phenomenon when compared to the other Guipúzcoa regions. The impact of marriages between first cousins from immigrant groups on the regional inbreeding levels represents an interesting result as well. Geographic and demographic factors seem to be related both to the extent of marriages as well as to the number of potential mates within populations, which, in turn, are associated with mean inbreeding levels. Altitude seems to show weak relationship with population distribution and population consanguinity variables. Nevertheless, levels of endogamy appear positively correlated with consanguinity rates and mean inbreeding coefficient and, inversely related-but not statistically significant- to mean village sizes. First cousin marriages yield the highest levels of exogamy and exogamous M22 marriages were mostly concentrated within short (1–10 km) and long-range marital distances (>50 km). The aveaage values of Goierri have been compared with a consanguinity data set of some selected Spanish mountain populations taken from the literature. One of the main results is that geographic and demographic variables are poorly correlated with the most important inbreeding parameters. However, different clusters of populations can be observed with specific characteristics for each of them, not highly correlated with geography.     

Consanguineous marriage among the Fulani

The Fulani are a broad ethnic category of nomadic and seminomadic pastoralists and agropastoralists living in the semiarid Sahel region of sub-Saharan Africa. The Fulani are patrilineal, patrilocal, and moderately polygynous, with arranged first marriages accompanied by the payment of bridewealth, ideally in the form of cattle. Consanguineous marriage is frequent, with first or second cousin marriage preferred. In this paper we present data on levels of consanguineous marriage among the Fulani of northern Burkina Faso and test the hypothesis that inbreeding may be more frequent when there is a scarcity of cattle available, since bridewealth demands are thought to be reduced with close-kin marriage. Among 308 women's marriages, 203 (65.8%) were between kin up to and including second cousins, and 102 (33.1%) were between nonkin. Among 276 men's marriages, 196 (71.0%) were between kin up to and including second cousins, and 77 (27.9%) were between nonkin. The mean population inbreeding coefficient (alpha) was 0.0355 for women, and 0.0374 for men. No increase was found in population levels of inbreeding estimated from marriages contracted after the droughts of 1973 and 1984, which drastically reduced the Fulani's cattle stocks. However, a significantly higher rate of consanguineous marriage was found in families owning the fewest cattle.     

Inbreeding in Gredos mountain range (Spain): contribution of multiple consanguinity and intervalley variation.

The present paper examines consanguineous marriages occurring between 1874 and 1975 in three valleys (Tormes, Alberche, and Tiétar) in the Sierra de Gredos mountain range, Avila province, Spain. Information was obtained from parish registers of 42 localities, corresponding to a total of 41,696 weddings. Consanguineous marriages were defined as those up to the third degree of consanguinity (second cousins). From 1874 to 1975 the percentage of related mates was 4.45% and the inbreeding coefficient was 0.0011868 (for 1874 to 1917 corresponding figures up to the fourth degree were 16.44% and 0.00 19085, respectively). In order to ascertain the characteristics and evolution of mating patterns in Gredos, the contribution of each degree of kinship was analyzed as a whole and then for each valley separately. Regarding total consanguineous marriages in Gredos, there is a low frequency of uncle-niece matings (0.21%) and a first-second cousin mating ratio (C22/C33) of 0.23 (up to the third degree of consanguinity). Before 1918 multiple matings (i.e., those involving more than a single relationship) accounted for 19.16% of consanguineous marriages (up to the fourth degree). The observed frequencies of multiple consanguineous marriages was, on average, about twice that expected at random, and the proportion of such marriages to total inbreeding was 34.65%. The temporal change of the Gredos inbreeding pattern was characterized by a recent decrease; the highest inbreeding levels correspond to the period from 1915 to 1944. Finally, intervalley differences (maximum inbreeding coefficient in the Tormes, minimum in the Tiétar) are interpreted considering the geography, population size, and population mobility for each valley     

Consanguineous marriages in Afghanistan

The present cross-sectional study was done in order to illustrate the prevalence and types of consanguineous marriages among Afghanistan populations. Data on types of marriages were collected using a simple questionnaire. The total number of couples in the study was 7140 from the following provinces: Badakhshan, Baghlan, Balkh, Bamyan, Kabul, Kunduz, Samangan and Takhar. Consanguineous marriages were classified by the degree of relationship between couples: double first cousins, first cousins, first cousins once removed, second cousins and beyond second cousins. The coefficient of inbreeding (F) was calculated for each couple and the mean coefficient of inbreeding (α) estimated for each population. The proportion of consanguineous marriages in the country was 46.2%, ranging from 38.2% in Kabul province to 51.2% in Bamyan province. The equivalent mean inbreeding coefficient (α) was 0.0277, and ranged from 0.0221 to 0.0293 in these two regions. There were significant differences between provinces for frequencies of different types of marriages (p<0.001). First cousin marriages (27.8%) were the most common type of consanguineous marriages, followed by double first cousin (6.9%), second cousin (5.8%), beyond second cousin (3.9%) and first cousin once removed (1.8%). There were significant differences between ethnic groups for the types of marriages (χ2=177.6, df=25, p<0.001). Tajiks (Soni) and Turkmens (also Pashtuns) showed the lowest (α=0.0250) and highest (α=0.0297) mean inbreeding coefficients, respectively, among the ethnic groups in Afghanistan. The study shows that Afghanistan's populations, like other Islamic populations, have a high level of consanguinity.     

Genetic structure of the Utah Mormons: isonymy analysis

Isonymy analysis is reported for a sample of 188,895 marriages extracted from the Utah Genealogical Database. Inbreeding rates estimated by isonymy are low, ranging from 0.005 for the earliest marriage cohort (1800-1809) to 0.0008 in the most recent cohort (1950-1959). The inbreeding values decrease considerably through time, but they are consistently higher than inbreeding values estimated from pedigrees. Several explanations are offered for this, including polyphyletism of surnames and the presence of Scandinavian patronyms in this population. Random isonymy between subdivisions is also compared with random kinship estimated from migration matrices. In terms of within-subdivision kinship, the two approaches yield similar results. However, the results are quite dissimilar for between-subdivision kinship. This reflects the recent and nonrandom settlement of Utah by different ethnic groups with different surname distributions. In later time periods, the correlations between the two types of kinship estimates increase, showing that migration patterns (which are strongly determined by geographic distance) exert an increasing influence on the distribution of surnames. Logistic regression is performed on a subset of marriages (n = 88,202), using isonymous vs. nonisonymous marriage as the dependent variable. The independent variables are year of marriage, geographic distance between husband's and wife's birthplaces, endogamous vs. exogamous marriage, and population sizes of husband's and wife's birthplaces. Year of marriage and geographic distance are shown to be significant independent predictors of isonymous marriage.     

Consanguineous marriage in a newly developed country: the Qatari population

This study examines the frequency of consanguineous marriage and coefficient of inbreeding in the State of Qatar. The study was conducted in semi-urban areas of Doha between January and May 2004. A sample of 1515 married Qatari females aged 15 years and over participated. The degree of consanguinity between each female and her spouse, and degree of consanguinity between their parents were recorded. The rate of consanguinity in the present generation was high (54.0%) with a coefficient of inbreeding of 0.02706. The commonest type of consanguineous marriage was between first cousins (34.8%). Double first cousin marriages were common (3.1%) compared with other populations. The consanguinity rate in the State of Qatar has increased from 41.8% to 54.5% in one generation.     

Consanguineous marriages in the population of Sheikhupura (Punjab), Pakistan

This study was based on 1007 couples from the Sheikhupura population. The proportions of various parental relationships were: 0.3784 1st cousins, 0.0318 1st cousins once removed, 0.0784 double 2nd cousins, 0.1033 bradari distant relations, 0.3416 bradari, and 0.0665 unrelated parents. Mean paternal ages in unrelated couples are significantly higher than in 1st cousins, double 2nd cousins, and bradari relations. The differences in paternal and maternal ages are significantly higher in unrelated relations as compared to 1st cousins and double 2nd cousins. Procounced effects of consanguinity on parental deaths and neonatal deaths were observed in 1st cousin marriages compared to other relationships. Juvenile and infant deaths show comparatively less effects of consanguinity in 1st cousin marriages. Mean coefficient of inbreeding calculated for this population was 0.0271. Lethal gene equivalents calculated were 1.5424. The added risk of affected children in 1st cousins over that of unrelated parents was 4.82%. The results suggest that the deleterious genes show their effects more in the prenatal than in the postnatal period.     

云南九个民族中的近亲结婚调查

对云南9个民族[傣、哈尼、彝、布朗、基诺、拉祐、苦聪(人)、回、汉]共11,589起婚姻作了调查。发现:(1)城、乡之间,各民族与地区之间,近婚率差异极显著。(2)许多民族的近婚率均较国内发达地区同一民族高。(3)姑舅亲、倒姑舅、两姨亲及3/2表亲占9个民族近婚总数的84.7％。(4〕9个民族的平均近交系数同样较国内发达地区同一民族高,其中苦聪人的平均近交系数(0.018579)是目前国内最高数值之一,即使平均近交系数最低的汉族(0.001935)也明显高于北京、湖北宜昌和上海市区的汉族的平均近交系数。     

Socioeconomic, demographic, and geographic variables affecting the diverse degrees of consanguineous marriages in Spain

In a population the inbreeding coefficient alpha is determined by the relative incidence of the various degrees of consanguineous marriages--uncle-niece or aunt-nephew (C12), first cousin (C22), first cousin once removed (C23), second cousin (C33)--which may be related to temporal, geographic, demographic, and economic factors. Using published information from Spain corresponding to urban and rural areas, in this article we seek to establish how each specific relationship behaves with respect to geographic, demographic, and socioeconomic factors, to determine differential urban-rural patterns, and to study whether the diverse types of consanguineous matings relate homogeneously to these factors. For this purpose we performed multiple regressions in which the dependent variables were the different degrees of consanguinity previously selected and the independent variables were geographic, demographic, and economic factors. Our results indicate that the various types of consanguineous marriages in Spain are more conditioned by geographic, demographic, and economic variables than by the inbreeding level alpha (the coefficient of determination was between 0.22 and 0.72; the maximum for alpha was 0.35). A regional pattern exists in Spain and corresponds to close and to remote kinship, which may be mainly related to economic and family factors. Close relationships appear to be more associated with economic variables, whereas second-cousin marriages correspond largely to rural areas of the Spanish Central Plateau.     

Consanguinity and prereproductive mortality in the Utah Mormon population

To test the effects of parental consanguinity on mortality among offspring, inbreeding coefficients were estimated for 303,675 members of the Utah Mormon population who were born between 1847 and 1945. Although consanguinity has been relatively rare in this population, the large sample size permitted the identification of more than 3,500 inbred offspring. Among the offspring of unrelated parents, 13.2% died before the age of 16. Significant elevations in prereproductive mortality were seen among the offspring of first-cousin marriages (22%) and among the offspring of closer unions (32%). The cor- responding relative risks are 1.70 (95% confidence limits = 1.52, 1.91) and 2.41 (95% confidence limits = 1.59, 3.41), respectively. Other categories of relationship did not produce significant elevations in offspring mortality. Similar results were obtained when a case-control approach was used to remove the effects of socioeconomic variation. Consistent with many other studies of populations with low consanguinity rates, this population experienced a relatively high absolute increase in mortality among the offspring of first-cousin marriages (9%). Preliminary evidence is offered for the hypothesis that mortality differentials are larger in populations with low inbreeding and low mortality because nongenetic causes of death do not obscure the effects of consanguinity.     

Consanguineous marriages in the province of Antalya, Turkey

To assess the trends in the frequency and the medical effects of consanguinity in the south coast of Turkish population using local and national data in the last 11 years. This cross-sectional study was carried out in Manavgat province, which is a major tourism center on the Mediterranean coast of Turkey. The authors studied consanguineous marriages in rural and urban population in the Mediterranean coast, Manavgat province, Turkey, via a 1500 random survey sample of married couples. There has been a significant increase in the incidence of consanguineous marriages in rural areas (40.7%) since 1989 in the southern population of Turkey. The results showed that the most frequent type of marriage was between the first cousins. It is found that there is no statistically significant difference between the consanguineous and non-consanguineous marriages in the different age groups. The results were discussed on the basis of educational status, reasons for having consanguineous marriages and the general medical effects as well as with the relation of congenital malformations. The custom of consanguineous unions in the Mediterranean population of Turkey is still extremely high, and preventive measures should be done to decrease its frequency and associated complications.     

Isolation and marriage patterns in four South Tyrolean villages (Italy) during the nineteenth century

No information is currently available on the marriage patterns of German-speaking communities of the South Tyrol area. The aim of this study is to investigate the reproductive isolation of four South Tyrolean mountain villages during the 19th century. Data about 3953 marriages were drawn from existing pedigrees and completed with data from the parish registers of the studied villages to calculate the following indicators: age at marriage, endogamy, inbreeding from dispensations and from isonymy and repeated pairs of surnames among couples. The results show high levels of endogamy (78-87%) and an elevated age at marriage in all the studied villages. The percentages of consanguineous marriages (10-33%) vary considerably but result overall in relatively low inbreeding values (alpha 0.0015-0.0036; Ft 0.0098-0.0138). Levels of endogamy are consistent with the geographic characteristics of the area, while inbreeding values are lower than those observed in previous studies on Alpine communities. This is due to a low frequency of marriages between close relatives, probably related to the peculiar demographic and cultural characteristics of the studied populations that differentiate them from neighbouring Italian-speaking villages.     

Effects of polygyny and consanguinity on high fertility in the rural Arab population in South Jordan

Based on the authors' interview survey for 608 randomly selected women of the rural Arab population in the South Ghor district of Jordan, this paper examined the effects of polygyny and consanguinity on high fertility, which was recognized as natural fertility. The prevalence of polygynous and consanguineous marriages was 28.0% and 58.1%, respectively, largely reflecting the population's traditional marriage customs. The findings highlighted a significantly higher total marital fertility rate (TMFR) in the monogamous wives (10.5) than in the senior polygynous (8.1) and junior polygynous wives (8.6); the TMFR did not significantly differ among the wives of non-consanguineous, first-cousin and second-cousin marriages. The formation of polygynous marriage was decided by the husband, mostly as a result of his senior wife's infecundity or sub-fecundity, and the age of the husband at marriage to his junior polygynous wife was high in many cases, leading to a decline in this wife's fecundity.     

Estimates of cousin marriage and mean inbreeding in the United Kingdom from 'birth briefs'

From 626 ascendant genealogies, known as 'birth briefs', deposited by members of the Society of Genealogists in their London library, rates of consanguineous marriage and coefficients of mean inbreeding (a) of offspring were estimated for cohorts of marriages contracted in the late nineteenth and early twentieth centuries. The rate of first cousin marriage in the generation estimated to have married during the 1920s was 0.32%, with no marriages between second cousins. The mean inbreeding coefficient for the offspring of these marriages was estimated as 0.0002. In the previous generation 1.12% of the marriages were between first cousins, and the estimate of mean inbreeding was 0.0007. Comparison with data taken from the published literature suggests that the levels of cousin marriage observed are consistent with a secular decline during the late nineteenth and twentieth centuries.     

Spatial and temporal variation of consanguinity in Italy

Genetic structure of Italian population is described as regards the level of inbreeding measured through the frequency of consanguineous marriages during a long period of time in different geographical areas. Analyses of spatial and temporal variation of the different types of marriages between close biological relatives allow us to point out the major factors responsible for the availability of cousins to marry within a specific area: population size, fertility, mortality and migration rates and, in general the demographic structure, changing over time and greatly affected by variation in the socio-economic structure. A deepened analysis, within each consanguinity degree, of the various pedigrees differing in the sex of ancestors, give information on the type of migration (patrilocal or matrilocal) occurred in various parts of Italy, as probable consequence of differential type of economy (for instance: pastoral or agricultural in Sardinia). Moreover, a cultural factor of varying intensity could be recognized in the greater observed frequency of marriages in which the nearest ancestors are females, interpreted as a tendency to maintain family ties by mothers of consanguineous mates.