Depending on your culture, cousins marrying cousins will either be a normal occurrence or something hugely taboo.
The contrast in opinions on the topic became especially apparent this week, after NHS England’s Genomics Education Programme shared a blog discussing the ‘various potential benefits’ of first-cousin relationships.
The article claimed ‘stronger extended family support systems and economic advantages’ were among these advantages, but it was later removed from the site after widespread backlash.
Following the news, Tory MP Richard Holden told the Daily Mail that the Conservatives planned to crack down on marriage between first cousins, while health secretary Wes Streeting said on LBC radio: ‘First-cousin marriages are high risk and unsafe, we see the genetic defects it causes, the harm it causes… That advice should never have been published.’
However, an NHS spokesperson said that although it recognises the scientific evidence surrounding an increased risk of birth defects in children born to blood-related parents, it aims to inform parents in a ‘respectful way’.
The fact is, though, an estimated 10% of all marriages worldwide are between first or second cousins, and the legalities, history and research around this practice – both in the UK and abroad – aren’t as rigid as the current debate may have you believe.
Is it legal in the UK for cousins to get married?
Here in Britain, it’s legal for first cousins to marry.
Prince Philip and Queen Elizabeth II were third cousins, but the likes of Charles Darwin and HG Wells are among the various well-known figures who married their first cousins.
That doesn’t mean cousins getting married haven’t come under fire, however, and there have been growing calls for the practice to be banned in recent years.
Elsewhere, it’s banned in countries like China, South Korea, the Philippines, Belgium, Lithuania and various US states, with Norway and Sweden becoming the latest nations to introduce laws against first-cousin marriage.
Family members who are illegal to marry
In the UK, although first cousin marriages are legal, you are not allowed to marry the following:
- Mother
- Father
- Son
- Brother
- Sister
- Grandparents
- Grandchildren
- Uncles or aunties
- Nieces or nephews
Most of these also include half-relatives, although when it comes to step-family, the rules are less clear. In these cases, both parties must be aged over 21, and the younger individual must not have been treated as a child of the older person’s family.
Why first cousin marriage is so controversial
Stigma around the practice is partly cultural, but concerns tend to come from research suggesting children can suffer from a higher rate of disease or infant mortality. The evidence is far from clear-cut though.
A long-running study by the BBC looking at first cousin marriage within the Pakistani community in Bradford found a higher incidence of genetic conditions and ill health in children born to cousins, revealing a child of first cousins has a 10% lower chance of reaching a ‘good stage of development’ than one whose parents are not related.
But Professor Sam Oddie, a consultant neonatologist and researcher at Bradford Teaching Hospitals highlights that this could be less about the parents being cousins specifically and more about endogamy, where people from the same ethnic community share common genes.
Other issues potentially impacting health issues include parental age, smoking, alcohol use and assisted reproductive technologies.
According to Alan Bittles, from the Centre for Comparative Genomics in Australia, the risk of birth defects rises from roughly 2% in the general population to 4% for first cousins, but the adjunct professor and research leader claimed ‘it would be a mistake to ban it’ and potential issues should be ‘kept in perspective’.
Similarly, Professors Diane Paul of the University of Massachusetts in Boston and Hamish Spencer of the University of Otago in Dunedin, New Zealand compared the risk of birth defects in first-cousin relationships to those of mothers over 40.
In regards to countries that have banned first-cousin marriage, Spencer stated: ‘Neither the scientific nor social assumptions behind such legislation stand up to close scrutiny. Such legislation reflects outmoded prejudices about immigrants and the rural poor and relies on over-simplified views of heredity. There is no scientific grounding for it.’