Can You Marry Your Cousin?

Consider this list:

Charles Darwin married his first cousin.

Albert Einstein’s parents were first cousins. Then Albert married his own first cousin. Elsa Lowenthal, Einstein’s second wife, was his first cousin on his mother’s side. In fact, they were also “double cousins.” Lowenthal also happened to be Einstein’s second cousin on his father’s side.

Franklin Delano Roosevelt and Eleanor Roosevelt were fifth cousins, once removed (a chart showing their relationship is available at http://www.gwu.edu/~erpapers/teachinger/q-and-a/q6.cfm).

John Adams married his third cousin, Abigail Smith.

John F. Fitzgerald, former mayor of Boston and grandfather of John F. Kennedy, married his second cousin, Mary Josephine Hannon.

Rudy Giuliani, former mayor of New York, married his second cousin once removed, Regina Peruggi

Samuel F. B. Morse, inventor of the Morse Code, took his first cousin once removed, Sarah Elizabeth Griswold, as his second wife.

Johann Sebastian Bach married his second cousin, Maria Barbara Bach.

Jerry Lee Lewis married his first cousin, who was 13 years old at the time.

Edgar Allan Poe married his cousin Virginia Clemm in Baltimore in 1835. She was 13 years old at the time.

At the age of 21, Queen Victoria married her first cousin, Prince Albert of Saxe-Coburg-Gotha. For the next 20 years, they lived in close harmony and had a family of nine children, many of whom eventually married into the European monarchy.

Princess Mary of Teck (later to become Queen Mary) married her second cousin, once removed, King George V.

The above is an abbreviated list. A much longer list of notable couples who were cousins may be found at http://en.wikipedia.org/wiki/List_of_coupled_cousins.

Thousands of people marry their first or second cousins every year. One article I read claims that twenty percent of all married couples in the United States are cousins. That reference comes from an article at http://abcnews.go.com/2020/Stossel/story?id=2395516&page=1 that offers no source citations. I am not sure I believe it.

Once you go further apart than second cousins, the issue becomes more difficult. After all, can you name all your third cousins and fourth cousins and those even further away in the family tree? Very few people can do that. There is always a strong possibility that you unknowingly married a distant cousin. The only way to find out is to research both of your family trees. To be sure, all of us are related to each and every other person somewhere back in history. Therefore, you probably married a distant cousin. The difficulty lies in proving it.

In America, marrying your first cousin is legal in 25 states. Some lists claim that 26 states allow cousin marriage. The confusion apparently stems from the laws of North Carolina, where double cousin marriage is specifically prohibited, but marriages amongst “normal” cousins (those who are not double cousins) are allowed. (N.C. Gen. Stat. § 51-3). All first cousin marriages are permitted in the other 24 states.

Six states ban marriage between first cousins once removed, i.e., marrying the son or daughter of your first cousin. No states ban marriages between second cousins.

Some states have more “interesting” laws, such as Arizona: first cousins may marry only if both are sixty-five years of age or older.

A list of laws in each state may be found at http://www.cousincouples.com/?page=states. Click on the appropriate state in the map to view each state’s laws.

No European country prohibits marriage between first cousins. It is also legal throughout Canada and Mexico to marry your first cousin. The U.S. is the only western country with cousin marriage restrictions.

Many people believe that the Bible is a higher authority than the laws of men. In Leviticus, Chapter 18 (KJV), God tells us that we are not to have sexual relations with a long list of relatives, but the word “cousin” is absent from the list. Leviticus does deny marriage to “any close relative,” and scholars have long debated whether or not that includes cousins. However, the Bible contains many instances of cousin marriage. For instance, Zelophehad’s daughters, Mahlah, Tirzah, Hoglah, Milcah and Noah, married their cousins on their father’s side (Numbers 36:1-11). According to that book, the important result was that “their inheritance remained in the tribe of their father’s clan.”

The Catholic Dictionary finds that Christ’s parents– Joseph & Mary– were first cousins. Not all Protestants agree. More cousin marriages listed in the Bible may be found at http://www.cousincouples.com/?page=religion.

The most common argument against cousin marriages is the increased risk of inherited diseases and birth defects. Indeed, there is some increased risk although the numbers appear to be small.

Non-related couples have a 2-3% risk of having children with birth defects. Couples who are first cousins double that risk to a 4-6% risk. Second cousins have little, if any, increased chance of having children with birth defects, according to the book “Clinical Genetics Handbook.” (Source citation: http://www.cousincouples.com/?page=facts).

Many genetic diseases are caused by recessive genes. To get the disease, you must obtain the bad gene from both parents. The greater the genetic similarity between your parents, the greater your chance of getting two copies of the bad gene.

Charles Darwin, who knew something about genetics, married his first cousin, and they raised exceptional children. All of Darwin’s children were healthy, had no known birth defects, and most of them apparently were either geniuses or near geniuses.

An interesting side issue is called pedigree collapse. When two individuals share an ancestor, the number of distinct ancestors of their offspring will be smaller than it could otherwise be. For example, a single individual today has more than 30 generations going back to the High Middle Ages with roughly a billion ancestors, more than the total world population at the time.

NOTE: This is impossible, of course. Nobody has more ancestors than those on the face of the earth. Duplicate ancestors (the same person appearing in multiple places in the family tree) will always appear in every person’s ancestry chart if we research and find every ancestor. However, for the moment, let’s focus only on the math involved.

A single individual occupies multiple places in the family tree when the parents of an ancestor are cousins (sometimes unbeknownst to themselves). For example, a person with no cousin relationships amongst his or her parents or grandparents has eight great-grandparents. Anyone whose parents were cousins only has six great-grandparents instead of the normal eight. One set of great-grandparents will show up twice in the ancestors chart. Going back to earlier and earlier generations results in a smaller and smaller number of ancestors when compared to the ancestry charts of the offspring of “unrelated” couples. This reduction in the number of ancestors is called pedigree collapse. It collapses the binary tree (two parents, four grandparents, eight great-grandparents, and so on in a binary progression).

Aside from the genetics, the legal issues, and the genealogies involved, social problems also arise. For instance, having a marriage is one thing, but going through a divorce is something else. You can move on from an ex-spouse or ex-lover, but there’s no such thing as an ex-cousin. How are your parents and your ex’s parents supposed to handle a nasty divorce or a breakup? How can they support their kids without antagonizing their siblings and their siblings’ kids? You’ve wrecked your whole family.

Avoiding one’s undesirable mother-in-law is already difficult in a normal marriage. What do you do if she is already “in the family” before marriage?

Each of us has millions of distant cousins. My belief is that most Americans are tenth cousins (or closer) to every other American. Some geneticists believe that everybody on Earth is at least 50th cousin to everybody else.

Chances are that you and your spouse were already related before your marriage. You are probably also related to Barack Obama, Mitt Romney, George Washington, Abraham Lincoln, Jefferson Davis, Walt Disney, Elvis Presley, Bill Gates, Sarah Palin, Arnold Schwarzenegger, Steve Jobs, Clint Eastwood, Hillary Rodham Clinton, Susan B. Anthony, Rosa Parks, all the Popes, Adolf Hitler, and a few billion other people as well.

29 Comments

I married my first cousin once removed.

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I don’t have any cousin marriages in my ancestry–that I know of–until back in 18th c. Dutch NY. Partly this is, as Dick points out, the result of lack of research in particular lines. The Dutch church records are particularly good, which is why I’m aware of those cousin marriages. Some of these cause fits in online family trees because occasionally the cousins have the same names and near birthdates. People aren’t always careful to distinguish one from the other and have the wrong people marrying. In one case, several people have a woman b. 1725 marrying a man b. 1783, when the right woman of the same name is her cousin at some removes, b. 1781. This error is very easy to avoid. In a true cousin marriage, now matter how distant the cousinship, with or without removes, the life spans have to at least overlap!

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My Italian grandparents were first cousins…how they were allowed to marry in the Catholic church without a known dispensation is a mystery to me. On the plus side, I had to work a lot less on her genealogy! Hahaha

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In America, the possibilities of cousin marriages vary a bit based on geography. For example, the English Puritans, only 20-40,000 strong immigrated to New England in the 1630’s and 1640’s. This blood pool stayed “enclosed” until about the Revolution because it was basically a “closed society”. Many “early” (ie first and second cousin) marriages occurred. After the Revolution, many of the descendants of these New Englanders spread across the land to all 50 states. The same could be said for the Germans and Scots-Irish in the early to mid 1700s, the Irish from the potato famine circa 1850, the Italians and Jews in late 1800s and early 1900s. Small blood pools usually stay together for 2-3 generations and then begin to melt into the melting pot. Meanwhile, the blood from New England ancestors is spreading all over America today, but the percentage of that blood in one person is getting smaller and smaller with each generation – so marrying another New England descendant means a more remote cousin marriage with each passing generation.

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I have quite a few examples in my family history. One chap married his 1st Cousin, had several kids and when she died he married her sister and had more kids. On one marriage certificate I have it actually states that the couple are “cousins german” another name for 1st cousins. I know there have been religious objections in the past, but did not know that some of your states actually forbid such marriages.

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My Catholic paternal grandparents were second cousins and needed a dispensation from the bishop; late 19th century, Ohio.
Earlier in the century two of the same family were first cousins but although this seemed to be questioned, I have not seen any dispensation information.

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Don’t do like the Spanish Hapsburgs did. They got wiped out.

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Your comments strike me as a bit glib. With first cousin spousal breeding is a problem of dominant and recessive genes, and we all have a set of these. So dangerous recessive genes within the pool of offspring are real possible outcomes. For example, Queen Victoria and her consort Albert, had children who suffered from haemophilia, which may well have been the result of ‘in-breeding’ in the area of cousin to cousin marriage.

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    The issue with Queen Victoria’s hemophiliac descendants is not as a result of her marriage to her first cousin, Prince Albert.

    Victoria’s hemophilia gene was a spontaneous mutation originating in her own germ line, affecting one, but not both, of her X chromosomes. The couple did have one son who was a hemophiliac, but the problem mostly arose when several of her daughters, who were carriers but did not have hemophilia (each had one good X chromosome and one defective X which carried the hemophilia allele), married and bore sons, some of whom were hemophiliac, and daughters, some of whom were carriers, also.

    Here’s a chart to show some of the Victoria and Albert descendants:

    http://www.emersonkent.com/source_documents/victoria_hemophilia.htm

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A genealogical expert lecturing at the archives of the Canadian Province of New Brunswick told the class, “Everyone in New Brunswick is related to everyone else, one way or another.” So true! Rather than a family tree, the average New Brunswicker has a family web and needs genealogy software with cadcam-like plotting capabilities and a 3D printer in order to make sense of the relationships.

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I too have several cousin marriages among my ancestors. We have to also factor in the fact that in early times cousins were often the most likely to “be around”. For example at least in colonial US, population was sparser, and communities tighter knit, with families often sharing large land holdings or living in adjoining farms. Cousins were in close proximity and given random selection from among the available courting pool, cousins might have been the most acceptable, amenable, agreeable, accessible, etc., sharing “family” values and experiences not to mention family fortunes!! Families didn’t disperse with impunity to quite the same degree as they do today- now young people, both male and female, have a much easier and more available transport away from the home nest and bring home a lot more diversity. It never occurred to me to think about collapsing the family tree, just so long as we don’t cut it off completely. I rather enjoyed finding the overlaps in our history- It made for some very interesting explanations. The new diversity among mates will make future DNA explanations much spicier. As if studying our family stories, secrets and scandals weren’t spicy enough already!! And some folks thing Genealogy is a mild mannered sport!!

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My mother-in-law & father-in-law were 1st cousins, Catholic, and married in the old country. My girlfriend’s in-laws were 1st cousins and married also.

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My great-grandparents on mother’s were first cousins. There are several of my third & Four Cousins who married each other

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My husband and I are cousins at least two dozen times over, but no closer than 9th cousins. I discovered this by researching both of our ancestries. We both had ancestors in early New England, and in fact both of us had ancestors on the Mayflower although not the same ones.

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But half-sibling marriages have no real impact on a tree, correct? In Nelson Co KY, after the Catholic migration, I have the 1791 bond for John Baptist Dant to marry Elizabeth Shircliff (noted as widow) and in 1792 the marriage bond for his son Joseph Dant to marry the step-daughter of Jno. Bpt. Dant, Elizabeth Belinda Shircliff. I assume there is no impact on my tree and this would be the same as any other non-related marriage. It was interesting to me that all the estate documents for the deceased husband/father, Thomas Shircliff who died in Maryland, were filed in Nelson County KY. His papers moved with the migration!

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One of my grandmother’s came from the Anglo-Irish gentry and her parents were cousins as well as her maternal grandparents. Marrying someone not a cousin was the exception. The same with my southern relatives. It does get complicated!.

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My parents knew they were third cousins when they got married. After I started looking into both families, I found where two sisters married an uncle and nephew and yes, one is in each of their families. So it turns out they are third cousins, fourth cousins, and fourth cousin once removed. sure does make for less work filling out ancestor charts.

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Thank you for your article. It gave me several laughs today.
With my ancestors as part of the Puritan migration, I’ve also documented many unions of close relations. Thank goodness for the computerized sofetware programs to help keep it all straight for me!

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My 4th ggrandparents were first cousins, and since both of my grandmothers are from West Virginia I have so many cousin marriages I can’t even begin to count them.

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As someone else pointed out, “inter-marrying” of cousins was often a simple matter of PROPINQUITY. In the days before reliable roads and transportation, one often married a person of marriageable age who lived nearby. Often “nearby” meant “within walking or riding distance.” My grandfather was lucky enough to be the son of a champion (Missouri) mule breeder and typically rode a mule over to my grandmother’s house when he went courting!

In other news, one of my ggfather’s siblings moved to Mississippi where at some juncture, five Goad sisters married five Chandler brothers. OH MY…

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Re Albert Einstein: he didn’t have children with Elsa, his second wife -the two daughters were from her first marriage. Nor were his parents first cousins, though his paternal grandparents were pretty closely related. Even so, of his two sons from his first marriage, (to a completely unrelated woman) one had the mental health problems which occurred in these families intermittently.

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One minor quibble, Dick:

Darwin did not know about genetics. He did know about evolution.

Gregor Mendel knew about genetics, but he did not marry his cousin. He was a monk.

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Dick Eastman said “Charles Darwin, who knew something about genetics, married his first cousin, and they raised exceptional children. All of Darwin’s children were healthy, had no known birth defects, and most of them apparently were either geniuses or near geniuses.”

I’m not sure where this information is from but at least one study states otherwise. It can be read at http://www.sciencedaily.com/releases/2010/05/100503111420.htm

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There’s a big difference between half-sibling and step-sibling marriages. The first are genetically related, and the second are not. So step-sibling marriages, as mentioned in one of the comments above, would have no impact except to connect the two families by marriage a second time, in the second generation. They don’t lead to the “pedigree collapse” Dick mentions. Nor do any issues of genetic consequences for possible offspring occur. Half-sibling marriages, where the two people share one parent, would be illegal in all US states, and could have genetic consequences. I have one step-sibling marriage that I know of. A widowed gg grandfather married a widow. One of his sons married one of her daughters–they were step-brother and step-sister to each other. No genetic relationship at all. At a slightly further remove, another widowed gg grandmother remarried to a man who’d never been married. One of her daughters from her first marriage, not one I’m descended from, later married a cousin of her stepfather’s. Again, marriage involving step relatives has no potential genetic consequences.

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My late wife and I were 21st full cousins. We both descended, along different lines, from Edward III of England. The remarkable thing is not that we were cousins but that, in spite during the intervening centuries, of early or late marriages and the early or late births within those marriages, we ended up not only in the same generation, but just two years apart. We have six great grandchildren.

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Research of the records of my ancestors and relatives from Quebec indicates numerous marriages between first and second cousins.
This is but one example: My maternal grandfather’s parents married in Quebec in 1890; had nine children; and then discovered that they were second cousins. For a valid Church marriage and in order that their children could be their legitimate heirs, they had another wedding ceremony in 1909 with a proper Church dispensation from marriage between second cousins. That’s what their 1909 marriage record indicates.

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What should i do now? i am inlove with my father’s sister fourth son who is my first cousin. I am Tanzanian,in our country some of tribes allows and some they don’t,my tribe and his,are both not allow. But we love each other so much and our parent retrict it so badly. Tell me what to do pls.

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William J. Onderlinde January 5, 2017 at 4:57 pm

Actually I have 2 questions. If the two people are from different states, which state’s law would prevail, particularly regarding 1st cousins? Is it true that no state prohibits 2nd cousins to marry?

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    Under the US Constitution, a marriage which meets the legal requirements of the US state where the marriage takes place is entitled to be given “full faith and credit” by all the other 49 states. So the answer to your first question is, if two 1st cousins got married to each other in any state where it was legal for 1st cousins to marry, then that state’s law would prevail. As long as all the other requirements of that state’s law in effect at the time of the marriage had been met, then all the other states would have to recognize the marriage as a fully legal one.

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