What happens when cousins marry and breed?

In New Zealand we have laws that prevent same sex marriage, yet allow first cousins to marry. What are the odds of genetic mutation from first cousins marrying:

The inbreeding is computed as a percentage of chances for two alleles to be identical by descent. This percentage is called “inbreeding coefficient“.

Ironically the inbreeding coefficient for first cousins is 6.25% which is probably the same percentage as there are homosexuals in society.

What are the issues of inbreeding then?

A 1998 review found 1-4% increased morbidity for offsprings of first cousins compared to offsprings of unrelated parents. A 1994 review found 4.4% increased mortality for offspring of first cousins. After controlling for several sociodemographic factors, infant mortality for offspring of first cousins had odds ratios of 1.36, 1.28, and 1.32 for the neonatal, postneonatal, and infant period. There has been little research on how inbreeding affects common adult disorder although some preliminary evidence support effects on many such disorders including cardiovascular diseases and common cancers. Many previously not identified genetic disorders have first been recognized in highly endogamous communities and the mutation causing the disease may be unique to such communities.

A review of 48 studies of children born to cousins found that most of the children were healthy, with birth defects affecting 4% of births for consanguineous couples compared to 2% for the general population.

So we have laws that allow first cousins to marry and as a result have an increased risk of genetic deformities and illness. None of this happens with sam sex marriage and yet that is prevented by law?

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  • Peter Wilson

    I don’t really understand the relevance here. It sounds like we shouldn’t allow first cousins to marry, which is a legitimate issue I’m sure. Others may say the increased risks are miniscule and can be compared to extra risks associated with living close to power lines, say. Who knows?

    In fact, surely you’re arguing that sexual intercourse should be made illegal between cousins. Yet preventing sexual intercourse between consenting adults is a tricky one. More likely it should be a case of taking responsibility for one’s actions rather than legislating for morality.

    But I’m unconvinced as to the relevance to enabling same sex marriage, which is more like legislating to call to golf ball a hockey stick.

  • Graeme Edgeler

    You seem to have bought into the argument of the opponents of same-sex marriage that marriage is about procreation. Even if we prohibited first-cousin marriage, as some US states do, that wouldn’t stop them having kids.

  • Urban Redneck

    Long established societal mores in the West have generally put the kibosh on cousins marrying so there doesn’t need to be a law against something that is not countenanced by the wider culture. You liberals are so steeped in cultural Marxism – it is truly worrying.

  • A-random-reader

    The problem with prohibiting first-cousin marriage is that there is already a large number of married first cousins in this country.

    If the state annuls their relationships, what do you think their response would be?

  • Heisenbug TheGeek

    You need to take a look when the first-cousin marriages go into multiple generations, as in some tribal cultures (especially the Islamic world).  Look at the stats for Pakistani families in the UK and the proportion of children born with issues due to cosanguinous marriages into the nth generation.  It’s very, very nasty.  Oddly enough, you wouldn’t get the same issues from homosexual marriage.