On Some Novel Aspects of Consanguineous Marriages

Abstract

Consanguineous marriages, often viewed as incestuous and objectionable, are more widespread than commonly perceived. They integrate multiple facets of human adaptation: economic, cultural and genetic. The widely touted explanation for the origin and persistence of consanguinity is that it provides many socioeconomic benefits; however, this view may be too simplistic. The bias against consanguinity may preclude an objective understanding of this sociobiological puzzle. Inbreeding increases the speed of selection of beneficial recessive and co-dominant alleles, e.g. those that protect against diseases. In populations endemic with malaria, the prevalence of consanguineous marriages and the frequency of alleles protective against malaria are both very high. Thus, consanguinity could theoretically increase the relative fitness of a population under specific ecological conditions; sometimes, the overall genetic benefits may exceed genetic costs of inbreeding. We discuss some recent evidence from studies on inbreeding along with the reasons responsible for the mating strategy found in some human populations. We contend that a better appreciation of our inherent biases and potential genetic benefits of inbreeding in specific ecological conditions would help us to appreciate the wider picture of consanguinity.

Consanguinity and Primary Immunodeficiencies

“…Deleterious founder mutations have been reported in different consanguineous populations to be the underlying cause of a large spectrum of monogenic AR diseases including PIDs [12,13] . Recently, an interesting, but still controversial, potentially beneficial genetic aspect of consanguinity has been reported in the literature, suggesting that not only cultural and socioeconomic benefits may explain the origin and persistence of this behavior [14,15] . Indeed, it has been proposed that inbreeding may also increase the speed of selection of recessive alleles protecting against diseases such as malaria.…”

“…Indeed, it has been proposed that inbreeding may also increase the speed of selection of recessive alleles protecting against diseases such as malaria. This would allow a relative fitness of a population under particular ecological conditions, with a potential overall genetic benefit that might exceed the genetic cost of inbreeding [15] .…”

Applied cultural and social studies are needed for a sustainable reduction of genetic disease incidence

“…This proximal rational economic choice does however lead to ultimate issues with an accumulation of detrimental genetic variants within families, which can manifest as disease or sub-clinical defects (Adams and Neel, 1967;Al Talabani et al, 1998;Al-Gazali and Hamamy, 2014;Barbouche et al, 2011;El Mouzan et al, 2008;Magnus et al, 1985;Morton, 1958;Rezaei et al, 2006;Sheridan et al, 2013). Evolutionary theoretical models could also argue for some positive effects from consanguinity by rapidly selecting for beneficial recessive genetic variants which ultimately might benefit the population under a certain environmental selection pressure (Denic et al, 2008(Denic et al, , 2011. This type of selection does however come at a great individual cost which can not be acceptable in modern society (Bittles, 2011).…”

Random inbreeding, isonymy, and population isolates in Argentina

“…Furthermore, in many human populations, the mating between relatives is relatively frequent and stimulated for social, economic, and religious reasons. Overall about 10 % of the world's population is a result of consanguineous marriages (Bittles 2001;Denic et al 2011).…”