Sections

Services

Information

UK United Kingdom

Why not marry your cousin? Millions do

The topic of consanguineous marriage raises both interest and unease in Western societies. For those who are wondering, that big word means “marrying your cousin”. But why would anyone want to marry a…

American singer Jerry Lee Lewis famously married his cousin. flickr/dunechaser

The topic of consanguineous marriage raises both interest and unease in Western societies. For those who are wondering, that big word means “marrying your cousin”.

But why would anyone want to marry a cousin when there are so many other potential partners out there?

In generational terms this mode of thought is actually quite recent, and until the middle of the 19th century first cousin marriage was common in most Western countries, in part due to the shortage of available unrelated spouses in many outlying areas.

The times they are a'changin

The public mood in Europe and North America gradually changed, with a growing belief that marriages between couples who were close kin would result in unfavourable health outcomes for their offspring.

In the USA this reversal in attitude resulted in the introduction of state-based legislation to restrict or even ban marriages between first cousins.

Apart from 31 of the 50 US states, only China, Taiwan, the Koreas and The Philippines have introduced similar civil restrictions on first cousin unions, although regulations that curtail cousin marriage apply to members of the Roman Catholic and Orthodox churches.

Good law or prejudice?

Are these proscriptions justified, and if so why do they not apply to the rest of the world’s population, where a conservatively estimated 1100+ million people are married to a spouse who is a second cousin or closer, or are the offspring of such a marriage?

And what is the actual basis for our suspicion of consanguinity – is it primarily founded on religious, social or genetic grounds, and why has there been a recent upsurge in calls for a ban on first cousin marriage by politicians in many European countries?

These topics form the basis of my recent book Consanguinity in Context. As a geneticist I have been researching the health aspects of consanguineous marriage for over 30 years in South and Southeast Asia, the Middle East and North Africa, among migrant communities in Australia and the UK, and as adviser to the World Health Organization.

You won’t have children with webbed toes … really

Perhaps surprisingly to many, the genetic risks which have been associated with cousin marriage have been substantially overstated.

While some families and communities are indeed more likely to be affected by otherwise rare inherited diseases, a large majority of first cousin offspring show no disadvantage in health terms.

Further, many of the ill-effects on health that have been ascribed to “inbreeding” are more probably due to a wide range of adverse non-genetic factors, including young maternal age, very short birth intervals, trans-placental infection of the developing fetus with organisms such as rubella and cytomegalovirus, and inadequate nutrition both during pregnancy and early childhood.

In assessing whether or not consanguinity is “good” or “bad” there has been a notable failure to take into account the social and economic benefits of close kin marriage, which is a particularly important consideration in the poorer sections of societies where consanguinity is more common. Or to acknowledge that wives in consanguineous unions generally seem to enjoy more equal status.

Inevitable challenge

Given the entrenched opinions that the topic of cousin marriage often attracts, it is probable that these opinions will be challenged. But that is the nature of science, and I have undertaken extensive research to support the conclusions drawn.

The reality is that cousin marriage is something health planners and the general public will need to come to terms with in Australia’s multi-ethnic society.

It is not an issue we are accustomed to dealing with as a society, but once we remove historical prejudice, we find that consanguineous marriage is not the backwoods horror story we have been led to believe.

Which may perhaps provide some solace for those who have long harboured a secret crush on a cousin.

It also could add some spice to those dreary family get togethers.

Articles also by This Author

Sign in to Favourite

Join the conversation

21 Comments sorted by

  1. Peter Fox

    Medical doctor

    Sorry to be pedantic, but consanguineous is derived from the latin con + sanguin, meaning 'same blood'. Not just cousins.

    report
    1. Susan Hemruth

      Luftmensch

      In reply to Peter Fox

      Yes, that's right - you can't marry someone with the same blood type.

      report
    1. James Walker

      logged in via Facebook

      In reply to Ian Donald Lowe

      two other words: social networking.

      It's not just genetic inbreeding that's a problem - there's also social inbreeding. Marrying something from a different family means that you are exposed to a different lifestyle/outlook, and avoid insular clannishness.

      report
    2. Alan Bittles

      Adjunct Professor and Research Leader at Murdoch University

      In reply to Ian Donald Lowe

      Ian,
      Fair comment. But the aim of my article was to draw attention to the apparent over-emphasis on 'inbreeding depression', the extent of which in humans has been exaggerated by failure to control for important non-genetic variables.
      Best regards,
      Alan.

      report
    3. Alan Bittles

      Adjunct Professor and Research Leader at Murdoch University

      In reply to James Walker

      James,
      Also a fair comment. However, in many of the countries and societies in which consanguineous/endogamous marriage is favoured, the family/clan/tribe is regarded as a much more reliable source of help and protection than the government, e.g. as currently in the Arab Spring.
      Best regards,
      Alan.

      report
  2. Blair Donaldson

    logged in via Facebook

    consanguineous should be kept in the family (I know, bad pun)

    report
  3. Dan Lawler

    logged in via Twitter

    Why not kill a man? You know ... just to watch him die.

    report
  4. Emma Anderson

    Artist and Science Junkie

    I'm surprised the author didn't mention the economic reasons why people marry cousins. Like keeping the money in the family what with marriage being the tradition of sharing property.

    report
    1. Alan Bittles

      Adjunct Professor and Research Leader at Murdoch University

      In reply to Emma Anderson

      Emma,
      Please be assured that the economic reasons for favouring consanguineous marriage are extensively discussed in 'Consanguinity in Context'. The quite brief comment on the social and economic advantages of consanguinity included in my article reflect the word limit only.
      Best regards,
      Alan.

      report
  5. Philip Dowling

    IT teacher

    There is a lot of difference between families marrying first cousins and families marrying second cousins in terms of likely inheritance of familial genetic disorders.
    An interesting point of course is that given between 10 and 30% of children have a father other than their mother's husband, genetic testing is less likely to reveal cuckolding as easily in interreleated groups.

    report
    1. MsKatieKatieKay

      logged in via Twitter

      In reply to Philip Dowling

      Do you a reference for that 10-30% stat?

      This article suggests that the 10-30% stat is an urban myth and the real figure is likely to be 3% or less.

      report
    2. Grendelus Malleolus

      Senior Nerd

      In reply to Philip Dowling

      Philip - I think you will find that the "10-30%" refers to men who have sought a genetic paternity test and thus represent a self-selecting cohort of individuals who already have some reason to doubt paternity. They represent a very small proportion of men overall.

      report
    3. Alan Bittles

      Adjunct Professor and Research Leader at Murdoch University

      In reply to Philip Dowling

      Philip,
      Although the term 'cousin marriage' is used without further definition in the article, in my book the studies on the influence of consanguinity on fertility and early mortality are sub-divided into five separate categories: uncle-niece/double first cousin, first cousin, first cousin once removed, second cousin, and non-consanguineous.
      Best regards,
      Alan.

      report
    4. Richard Windsor

      logged in via Facebook

      In reply to MsKatieKatieKay

      Quoted by Jared Diamond in "The Rise and Fall of the Third Chimpanzee" page 73. After that, you are on your own .

      report
    5. Philip Dowling

      IT teacher

      In reply to MsKatieKatieKay

      I must admit that I don't have reliable figures. I used the range 10-30% because that seemed to be the range that some have quoted.
      I raised the issue because it would potentially be an issue in a small number of cases of first cousin marriages.

      report
    6. Grendelus Malleolus

      Senior Nerd

      In reply to Philip Dowling

      I'm not sure why it would be any more of an issue in first cousin marriages than in any other marriage but given the concern you mentioned about inherited genetic disorders would in not be preferable in your view for cuckolding to occur and thus reduce risk of familial disorders being passed to offspring?

      report
  6. Alan Bittles

    Adjunct Professor and Research Leader at Murdoch University

    Grendelus, MsKKK and Philip,
    I very much agree that the often cited figure of 10-30% non-paternity/paternal discrepancy almost certainly does not apply to the general population.
    A useful review of 17 studies which reports a 3.7% median paternal discrpenacy is:
    Measuring paternal discrepancy and its public health consequences.
    Bellis MA et al.
    Journal of Epidemiology and Public Health 2005, 59, 749-754.
    Best regards,
    Alan Bittles.

    report
  7. Gil Hardwick

    anthropologist, historian, novelist, editor and publisher at eBooks West

    Alan, I recall that we've had this conversation, some years ago now.

    For the moment, it's fair to say that most of the first-cousin marriages we have experienced here in Australia, especially those comprising multiple first-cousin marriages over several generations within the same two family lines (usually discernible in repeat surname binaries), were to cement strategic alliances and so retain extensive landholdings intact.

    My subsequent understanding of the process is that it had little to…

    Read more
    1. Gil Hardwick

      anthropologist, historian, novelist, editor and publisher at eBooks West

      In reply to Gil Hardwick

      An afterthought . . . .

      My view on the late 19C effort to discredit first cousin marriage is that it was a propaganda device to diminish and discredit large extended landholding families as part of state efforts at taking control of land as a basic factor of industrial production.

      It seems no mere accident to me that this propaganda effort coincided with the onset, progress and outcome of the American Civil War in particular, often mistakenly glorified as conducted to 'free the slaves' (which…

      Read more