Science says it's fine to marry your first cousin - Hawaii News Now - KGMB and KHNL

Science says it's fine to marry your first cousin

First cousins share only about 12.5 percent of their DNA, and it’s estimated that 4 to 7 percent of children born to them are likely to have birth defects. (Source: Pixabay) First cousins share only about 12.5 percent of their DNA, and it’s estimated that 4 to 7 percent of children born to them are likely to have birth defects. (Source: Pixabay)

(RNN) – After studying the genealogy of 13 million relatives, scientists determined that only social norms are keeping people from marrying their first cousins and having children because genetically, it’s not that different from having children with a more distant relative.

Scientists from across the world answered several questions on family and relationships – for instance, genetics only determines about 16 percent of a person’s life span – by studying data from millions of online genealogy profiles.

Their paper, published last Thursday in Science, also shed light on when and why marrying your first cousin became taboo.

In the 1700s, people typically married a fourth cousin, but starting around 1850, they began marrying more distant relatives, according to Science.

About 15 years later, by the end of the Civil War, many states began outlawing cousin marriages, Popular Science reports. Today, these marriages are banned in 24 states and allowed in 20. The last six pose various restrictions on the practice.

Yaniv Erlich, a Columbia University data scientist who devised the study, believes this changing social norm pushed people to look outside their surroundings and families for partners.

By 1950, married couples were, on average, seventh cousins, Erlich says, and that has lasted to modern times.

But according to research, there’s not much of a reason for it to be that way – at least, genetically speaking.

First cousins share only about 12.5 percent of their DNA, according to genetic testing company 23andMe. Comparatively, siblings, as well as parents and children, share about 50 percent.

When it comes to babies, it’s best to have genetic diversity. The lower the percentage of DNA a couple has in common, the less likely their kids will be to have major birth defects.

It’s estimated that 4 to 7 percent of children born to first cousins are likely to have birth defects, Popular Science reports.

But even children whose parents are more distantly related have a 3 to 4 percent chance for birth defects.

With 24 states banning marriage between first cousins and it being thought of as taboo, it’s unlikely this research will change humans’ marital practices, but it does reveal how closely everyone is related.

"[All] of us are something like 10th to 12th cousins of each other,” Erlich told Popular Science. "When you think about wars and violence all over the world, it’s all within the family."

Copyright 2018 Raycom News Network. All rights reserved.

  • Science & technology newsMore>>

  • Instagram co-founders resign from social media company

    Instagram co-founders resign from social media company

    Monday, September 24 2018 11:22 PM EDT2018-09-25 03:22:04 GMT
    Tuesday, September 25 2018 11:44 AM EDT2018-09-25 15:44:23 GMT
    The co-founders of Instagram are resigning their positions with the social media company.More >>
    The co-founders of Instagram are resigning their positions with the social media company.More >>
  • Bye bye bugs? Scientists fear non-pest insects are declining

    Bye bye bugs? Scientists fear non-pest insects are declining

    Thursday, September 20 2018 1:19 AM EDT2018-09-20 05:19:36 GMT
    Tuesday, September 25 2018 10:45 AM EDT2018-09-25 14:45:54 GMT
    (AP Photo/Don Ryan). FILE - In this May 26, 2010 file photo, a Coccinellidae, more commonly known as a ladybug or ladybird beetle, rests on the petals of a rose in Portland, Ore. A study estimates a 14 percent decline in ladybugs in the United States a...(AP Photo/Don Ryan). FILE - In this May 26, 2010 file photo, a Coccinellidae, more commonly known as a ladybug or ladybird beetle, rests on the petals of a rose in Portland, Ore. A study estimates a 14 percent decline in ladybugs in the United States a...

    Scientists are noticing fewer and fewer moths, ladybugs, fireflies and butterflies, but they can't quite quantify what's happening to flying insects because they never measured how many bugs there used to be.

    More >>

    Scientists are noticing fewer and fewer moths, ladybugs, fireflies and butterflies, but they can't quite quantify what's happening to flying insects because they never measured how many bugs there used to be.

    More >>
  • Japanese supply ship heads to space station after delays

    Japanese supply ship heads to space station after delays

    Saturday, September 22 2018 7:41 PM EDT2018-09-22 23:41:30 GMT
    Tuesday, September 25 2018 10:45 AM EDT2018-09-25 14:45:52 GMT
    (Kyodo News via AP). An H-2B rocket carrying the Kounotori 7 cargo spacecraft lifts off from Tanegashima Space Center in the southwestern Japan prefecture of Kagoshima, early Sunday, Sept. 23, 2018. The unmanned Japanese space capsule is heading to the...(Kyodo News via AP). An H-2B rocket carrying the Kounotori 7 cargo spacecraft lifts off from Tanegashima Space Center in the southwestern Japan prefecture of Kagoshima, early Sunday, Sept. 23, 2018. The unmanned Japanese space capsule is heading to the...
    An unmanned Japanese space capsule is heading to the International Space Station with 5,500 kilograms (12,000 pounds) of cargo including food, experiments and new batteries.More >>
    An unmanned Japanese space capsule is heading to the International Space Station with 5,500 kilograms (12,000 pounds) of cargo including food, experiments and new batteries.More >>
Powered by Frankly