We can see why people have such a strong fascination with twins. After all, you do not often get a buy one, take one deal when it comes to birth. But thanks to the progress of fertility science, there are now more twins than ever. As a matter of fact, the Centers for Disease Control and Prevention reported that 33 in 1,000 births in the US were twins. You might be familiar with terms like fraternal twins and identical twins, but there are other types out there. Keep reading to find out more amazing twin facts!
Also known as monozygotic twins, identical twins come from a single fertilized egg. It starts with the fertilization of the egg by a sperm. However, what makes it different from regular pregnancies would be the fact that the egg split into two not long after that. The two halves then grow into two separate babies.
Same Egg And Sperm
Identical twins come from the same sperm and egg, which is why their chromosomes are exactly the same. It is why they have the same sex and genetic characteristics, from the hair color to the eye color. But there are certain things, such as the space they had in the womb, that lead to small differences.
But how are fraternal twins, also known as dizygotic twins, different? This occurs when there are two separate fertilized eggs. It often happens when the mother releases two eggs at exactly the same time, only to be fertilized by different sperms. Unlike identical twins, they do not share the same set of DNA.
Different Egg And Sperm
Since fraternal twins are the result of two different pairs of egg and sperm, the resulting children only have half of their chromosomes in common. This is the case for any other set of siblings, even those who are not twins. That is the reason some fraternal twins look noticeably different or have different sexes.
Polar Body Twins
There is a third type that people call half-identical or polar body twins. Doctors say that this could explain why certain fraternal twins still look identical, but it has yet to be proven. An egg can split into two after its release, and the smaller one is known as a polar body. It can allegedly develop into a fetus if fertilized, but there is often too little fluid inside it for it to grow big and survive. If it survives, a sperm be fertilized by a sperm while the other half is fertilized by a different one. This is how polar twins are believed to be born. They come from one egg, so the chromosomes from the mother will be identical. However, they do not share chromosomes from the father. They are not necessarily the same sex.
Unusual Twin Pregnancies
Most of the time, twin pregnancies result in the birth of two healthy children. There are times, however, when unusual things happen at some point in the fertilization process. When these events take place at the beginning of a twin pregnancy, the parents should expect unique twins! But what does that mean?
Mirror Image Twins
Take a look at this certain type of identical twins. It occurs when the egg does not break into two a week after fertilization but 7 to 12 days later. By then, the embryo has developed a right and left side. The resulting twins might be identical, but they are mirror images of one another! Their hair might spiral in the opposite direction, while the teeth might come in on opposite sides of the mouth. It is also possible that one of them will be right-handed, while the other will be a leftie.
You probably know what conjoined twins are! They are twins who are connected to one another. This happens when a fertilized egg does not part all the way. This often happens when the split takes place 12 days or more after fertilization. Others, however, believe that the egg had already divided but fused back later on. The fusion is often seen in the abdomen or chest and varies. However, the twins typically share a vital organ or more. Sadly, they typically die in the womb or shortly after delivery. It is possible to separate the ones who survive, although it depends on where and how they are joined. Even though they share certain body parts, they are two individuals who can think for themselves.
As for parasitic twins, they are similar to conjoined twins but the smaller one depends on the bigger one for survival. Most of the time, the smaller twin is not fully formed or does not have certain vital organs. They form anywhere on the body of the bigger twin and appears as a small lump, a nonfunctional head, or additional limbs attached to the body. It could be a fetus in fetu, in which the parasitic twin forms inside the body of the bigger one. On the other hand, they might be acardiac twins. Twin to twin transfusion syndrome takes place when an identical twin receives too little blood flow, while the other gets too much. Acardiac twins go through a severe form of that, which involves the smaller twin being a torso with or without legs and a malformed or missing heart.
What are semi-identical twins? They occur when two different sperms fertilize an egg. In order to survive, the egg needs to split into two. On top of that, each half needs to have the right number of chromosomes. This is not common at all. In fact, there are only two reported cases of this type of twins.
Boy And Girl Identical twins
It is very rare, but it is possible for identical twins to have different sexes. They typically start as identical male twins, which means that they possess XY chromosomes and not XX. After the egg breaks off in two, one twin might lose the Y sex chromosome and turn to X due to a genetic mutation. This is known as Turner syndrome. There is only a single X chromosome, so the twin might look female but suffers from early developmental difficulties and eventual fertility problems. This does not affect the other twin.
Twins With Different Ages
Do you know what superfetation is? This is the fertilization of a second egg in an already pregnant woman. Yes, it happens. It is super rare since women normally do not release eggs once they fall pregnant. When such a thing happens in the same menstrual cycle, it is known as superfecundation.
Twins With Different Dads
On the other hand, there is also heteropaternal superfecundation. This is the term used to describe the process in which two eggs are released separately in the same ovulation cycle. They are then fertilized by two different fathers. This is fairly common in animals. While very rare in humans, it does happen.
Twins Of Different Races
There are three ways for this to happen, but they are all highly unlikely. First of all, they could be fraternal twins born to parents from different races. One twin will totally take after the mom, while the other inherits the father’s features. It might also happen when heteropaternal superfecundation takes place with two fathers from different races. Lastly, both parents might be biracial. The genes in the egg or sperm often lead to a mixture of racial features. However, the varying level of dominance might make the twins seem like they are from different races instead.
When Expecting Twins
Multiple births are usually high risk since they have a higher chance of difficulties. The mom might experience placenta previa, in which the placenta is low enough to cover the cervix. Placental abruption, in which the placenta is removed from the uterine wall, could also happen. Meanwhile, the placenta accrete involves the deep growth of the placenta into the uterine wall. Other possible issues are prematurity, low birth weight, gestational hypertension, gestational diabetes, and postpartum hemorrhage.
NASA Twins Mark And Scott Kelly
Are you familiar with the Kelly twins? The identical brothers were the subjects of a NASA study. Scott was sent to space, but Mark stayed on Earth. The goal of the study was to see how the body changed after a year in space. While his DNA did not change, Scott reacted to the environment in a different way.
Wrestling Icons Jey And Jimmy Uso
The Usos were twin identical twin brothers who have been a part of WWE ever since 2009. Jey and Jimmy launched their careers in Florida Championship Wrestling, the developmental brand of the campaign in the Sunshine State. They are both of Samoan descent and come from a family of wrestlers.
Retired NFL Stars Ronde And Tiki Barber
Before the twins went pro, Ronde and Tiki Barber played football at Cave Spring High School and then the University of Virginia. In college, Tiki was the running back and Ronde was the cornerback. In 2006, Tiki retired from the field and started commentating, but his brother only retired seven years after that.
Reality TV Personalities Drew And Jonathan Scott
You are probably familiar with the Property Brothers stars if you like reality TV. Drew and Jonathan Scott are identical twin brothers who work together to flip houses. The TV show went on to be a big hit and has even earned spinoffs, a web series, an app, an instructional book, and a radio show!
Tech Twins Cameron and Tyler Winklevoss
Are you familiar with the history of Facebook? If so, we bet that you already know that Cameron and Tyler Winklevoss sued Mark Zuckerberg for allegedly stealing their idea and using it to develop his own social media website. The twins were portrayed by Armie Hammer in The Social Network!
Hollywood Stars Tia And Tamera Mowry
The identical twin sisters got their start by starring in Sister, Sister back in 1994. But their big break came when they were cast to take on the lead roles in Twitches and its sequel. From 2011 up to 2013, they also had a self-titled reality TV show called Tia & Tamera.
Musicians Joel And Benji Madden
As you can see, it is not exactly rare for twins to work with each other in their chosen field! Just take a look at Benji and Joe Madden, who formed Good Charlotte and The Madden Brothers. Aside from the two musical groups, they also served as coaches on The Voice Australia from 2015 to 2016.
Advice Givers Abigail Van Buren And Ann Landers
Born Esther Pauline and Pauline Esther Friedman, Ann Landers and Abigail van Buren were best known for their work as advice columnists. They had been in their late thirties when they entered this field. The two of them became rivals when they both worked on the “Ask Ann Landers” and “Dear Abby” columns!
Wrestling Icons Brie And Nikki Bella
Nope, you are not seeing double! Nikki and Brie Bella are pro wrestlers who once made up a tag team called the Bella Twins on WWE. Aside from that, they were also on a reality show called Total Divas. Did you know that the two of them are now in the WWE Hall of Fame?
Musicians Sara And Tegan Quin
Together, this pair of identical twins make up an indie pop band that they named after themselves. Tegan and Sara Quin are both openly gay and advocate for LGBTQ equality. Aside from that, they are also passionate when it comes to causes such as cancer research, music education, and literacy.
Olympic Athletes Paul And Morgan Hamm
Up next, we have identical twin brothers who have reached the pinnacle of their career. Morgan and Paul Hamm are both retired Olympic gymnasts. It turns out that they are not the only talented gymnasts in the family. After all, their sister Betsy used to be on the USA Gymnastics Senior National Team as well!
Child Stars Dylan And Cole Sprouse
If these two guys seem familiar, it probably has to do with the fact that they were child stars! Do you remember The Suite Life Of Zack & Cody? Yep, these are the same guys. They went to New York University. Dylan now runs a meadery, while Cole continues to star in various Hollywood projects.
Fashion Designers Ashley And Mary-Kate Olsen
Let us now move on to famous fraternal twins. This must be the most hard-working pair of twins on the planet. Mary-Kate and Ashley Olsen were not even a year old when they launched their careers as child stars. They have since retired from acting and now run a luxury fashion brand called The Row.
Directors Ross And Matt Duffer
Do you love Stranger Things? If so, you should thank Matt and Ross Duffer! After all, they are the creators of the hit show. The two of them have always been close and worked as a duo throughout their careers. It must be awesome to work with someone you have known literally all your life.
Actors Giovanni And Marissa Ribisi
Marissa and Giovanni Ribisi are fraternal twins who both work as actors. Their mom is a manager, while their dad is a musician. They have a sister who works as a voice actress as well! Giovanni is best known for starring in Sneaky Pete, while Marissa was in Dazed and Confused. They both practice Scientology.
The next people on the list are all celebrities with twin kids! Actress Julia Roberts is best known for her role in Pretty Woman. She has three kids with Daniel Moder. They welcomed a set of twins in November 2004. Their twin daughter and son have a younger brother, who was born in June 2007.
Jennifer Lopez And Marc Anthony
There was a time when these two talented singers made up a power couple. During their decade of marriage to each other, Jennifer Lopez and Marc Anthony had a pair of fraternal twins on February 22, 2008. According to the father of the songstress, their family actually has a history of twins!
Known as the King of Latin Pop, the “Livin’ la Vida Loca” singer is the dad of two kids: Valentino and Mateo. He had the twin boys via a gestational surrogate mom. His kids were born in August 2008. Aside from his music career, the Puerto Rican singer is also known for his activism and humanitarian work!
This American star is best known for her portrayal of Claire Dunphy in Modern Family. When it comes to her personal life, Julie Bowen married a software developer and real estate investor by the name of Scott Phillips in 2004. The two of them had twins in May 2009, but they have since divorced.
Sean “Diddy” Combs
Also known as P.Diddy, Sean Combs has worked as a rapper, songwriter, record producer, and actor over the years. Aside from his amazing career as a performer, he is also the dad of six kids. He made it to the list as the dad of twin girls called Jessie James and D’Lila Star, whom he had with Kimberly Porter.
Neil Patrick Harris
If you watched Doogie Howser, M.D. and How I Met Your Mother, there is no way that you are not familiar with him. Neil Patrick Harris might have played a Casanova in the past, but he is actually a devoted dad and family man. In 2010, he and his husband had twins through a surrogate.
Here is another iconic singer with twin children! Madonna, also called the “Queen of Pop,” has six kids. Unlike others on the list, she is not related to the twins by blood. The “Like a Virgin” singer adopted a pair of twin girls from Malawi in February 2017. At the time of their adoption, Stella and Estere were four years old.
The gorgeous Zoe Saldana is famous for playing Uruha in Star Trek, Gamora in various Marvel movies, and Neytiri in Avatar. In June 2013, the actress tied the knot with an artist called Marco Perego. They welcomed a pair of twin boys in November 2014. The couple also had another son in February 2017.
Sorry, folks. The truth is that Chris Hemsworth has been off the market since 2010. He got married to Elsa Pataky in December of that year. Isn’t that sad? Oh, well. The Thor actor is actually the father of three kids. The couple had a daughter in May 2012 and a pair of twin boys in March 2014.
Is there anyone more talented than Mariah Carey? If there are, they are few and far in between. The singer has achieved a lot of things over the course of her career. Aside from her hit songs and albums, another achievement of hers would be giving birth to her twins with Nick Cannon: Moroccan and Monroe.
Michael J. Fox
Actor Michael J. Fox made a name for himself when he was cast to play Marty McFly in Back to the Future. He got married to Tracy Pollan on July 16, 1988. They have four kids between them. Their twin daughters Aquinnah and Schuyler are lovely young women who clearly take after their parents!
This former teen icon is best known for starring in some of the best movies of the ‘80s: Pretty in Pink, The Breakfast Club, and Sixteen Candles. The Brat Pack member is the mother of three kids. In 2003, she gave birth to a daughter. Six years later, she delivered a pair of fraternal twin boy and girl.
What is it with talented singers and twin children? Celine Dion, best known for singing hits like “My Heart Will Go On,” has three sons. Her eldest son is called Rene-Charles Angelil. She also gave birth to fraternal twins in October 2010. They are called Eddy and Nelson, named after French musician Eddy Marnay and South African President Nelson Mandela.
Most people are familiar with the concepts of identical and fraternal twins. However, there is a third type known as polar body twins. There are times when unique twins develop under unusual circumstances, although this is not common at all! Since twin births are rare, we can see why people are so fascinated by them. After all, it is like getting a “buy one, take one” deal!