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Zygosity DNA Test




SKU: ZYG - Twin Zygosity Category:


100% Accurate – Results in ONE Day

What is included: A 24 marker Identical Twin Zygosity DNA test, a Journey Genetic Testing DNA collection kit which includes USPS Priority shipping to you, detailed collection instructions, a prepaid return label for returning your DNA samples to the lab (USA addresses only for the prepaid return mailer), all lab processing fees, and results from our AABB accredited testing laboratory.

Who is included: Two individuals who want to determine if the are identical twins.  Additional individuals may be added at an additional cost as shown on the order form to determine if they are identical multiples (triplets).

How we send the DNA collection kit: USPS Priority mail. You will by emailed a tracking number from the USPS when the kit ships.

If you need to send a kit to more than one address: You have the option of sending additional testing kits to other addresses if needed. Each additional kit is $14.95 and includes USPS Priority shipping, collection materials, instructions, and a prepaid overnight return label for the samples. If you wish to send more than one kit please indicate this on the order form.

When your results will be ready: 1 business day after the lab receives all of the DNA samples.

Payment Options: We offer several ways to pay when you order a sibling DNA test. You can choose to pay with a credit, debit, or prepaid card with a VISA, MasterCard, Discover, or American Express logo. You may also pay through PayPal, and if you do not already have a PayPal account, you can set one up easily. We also financing options through Affirm. Affirm does not perform a hard credit check. Affirm offers both a Pay In 4 Payment plan, as well as offering up to a 12 month payment plan. Affirm is an independent company that we partner with, however the decision to extend financing is their decision alone.  

Our Zygosity DNA Test will provide answers to the question of whether twins, triplets, or quadruplets are identical or fraternal. Journey Genetic Testing is here to help you on this journey of self-discovery in learning the truth through DNA.

  • You Will Have Access To Our Expertise: We are leaders in DNA zygosity testing. Our Genetic Consultants have a deep understanding of zygosity and the latest advancements in DNA analysis.
  • We Guarantee Accurate DNA Results: Using the most advanced technology, our AABB parent lab will provide you with 100% accurate results. Your testing is performed twice to ensure your report is correct.
  • We Provide Everything You Need: Our kit is shipped USPS Priority and includes everything you need. We also include a pre-paid overnight return label for sending your DNA samples to our parent lab.
  • We Make Sure This Is An Easy Process: Our DNA test kit includes simple instructions for collecting your samples, making the process easy and stress-free.
  • Your Information Is Confidential: We know how sensitive personal DNA information is. This information will never be sold and will only be used to test for an identical twin relationship.
  • You Will Have Personalized Customer Support: Our friendly and knowledgeable team is here to answer any questions you may have along the way.

These FAQs will provide you comprehensive information about  Zygosity DNA testing. This includes how the testing works, when to use it, and what to expect from the process. If you’re looking for answers to your questions about twin DNA tests, you’ve come to the right place. Contact us today to learn more about our Twin Zygosity Test.

What Does Zygosity Mean?

Zygosity is a term used to describe identical twins who originate from a single fertilized egg, known as a zygote. During the early stages of development, this single egg splits into two embryos. As a result, twins born from this zygosity share the exact same DNA because they both come from one egg that joined with one sperm.

How Can I Tell If My Twins Are Identical Or Fraternal?

You can order a twin zygosity testing kit online, and it comes with four oral collection swabs along with clear instructions. Here's how the zygosity testing process works:

When the kit arrives, take two of the swabs and gently rub it on the inside of each of your child's cheeks. Keep doing this for about 15-20 seconds, making sure to collect enough cells from their mouth on the swab.

Allow the swabs to air dry, and then place them carefully into an envelope. Don't forget to write your child's name on the envelope for identification.

Send the envelope with the oral swab kit back to our lab, and we will analyze the samples in our laboratory.

You should receive the results of the DNA test in one business day. You will receive the results in a PDF that can be printed for a permanent copy, by email.

What Is A Twin Zygosity Test, And Do I Need One?

This test is used to discover if your twins are fraternal or identical. We provide you with a 100% accurate answer in just one business day.

Zygosity tests are important and well-liked because, surprisingly, they often show different results from what parents initially thought about their twins. Studies even reveal that many identical twins grow up thinking they're fraternal.

This mix-up occurs because doctors sometimes make mistakes when checking twin zygosity early in pregnancy, usually during an early ultrasound. They might forget to double-check their first diagnosis.

Sometimes, doctors mistakenly classify twins as fraternal when they see separate placentas at birth. However, this doesn't account for the fact that around 25% of identical twins actually have separate placentas.

Is it really important to know if your twins are identical or fraternal? In short, yes, it can help twins understand their connection better.

How Accurate Is Your Twin Zygosity Test?

This twin Zygosity DNA test will determine if your twins are identical (monozygotic) or fraternal (dizygotic). The results of our DNA tests are 100% accurate.

What Is Included In A Twin Zygosity Test Kit?

For only $109, our Twins Zygosity DNA Test kit includes everything you need:

- Simple, step-by-step instructions for taking the test and sending your samples to our lab.
- A pre-paid overnight label for returning your samples to us.
- Four packages of DNA collection swabs, with two swabs in each package.
- Individual DNA test sample envelopes for each person being tested.

If you need to test more multiples, you can easily add them to your order.

Once we receive your samples at our lab, we'll email your DNA results in just 1 business day.

Rest assured, your payment details are 100% secure, and we never use any information about you or your DNA for any other purpose. Your privacy is important to us.

Is A Parents DNA Sample Needed To Do A Twin Zygosity Test?

No. The testing is done only using the DNA from the twins. The results will be 100% accurate.

Do Twins Always Have The Same Father?

The answer may surprise you! While identical twins always have the same biological father, fraternal twins can have different fathers. This can happen if a woman has sexual intercourse with two different men around the same time when both embryos are conceived. While it is not common, we have seen this happen several times over the years.

This means in rare circumstances that the twins are also half-siblings!

Can You Have Twins Even If They Don't "Run" In Your Family?

Yes. The likelihood of having fraternal twins is greater in families with a genetic predisposition. However, it's important to note that individuals without a family history of twins can still have twins. Various other factors also play a role in determining the chances of having twins.

Does A Mother's Age Affect Twinning Rates?

Typically, older women have a greater likelihood of conceiving twins compared to younger women. A woman who is 35 years old is four times more likely to have fraternal twins. As women approach menopause, they undergo hormonal changes, leading to an increase in their follicle-stimulating hormone levels.

What Race Has The Most Sets of Twins?

African-American individuals assigned female at birth are more likely to have twins compared to individuals from other racial backgrounds. Asian Americans and Native Americans have the lowest rates for twins. Meanwhile, white individuals assigned female at birth have the highest rate of having higher-order multiple births, like triplets or more.

What Sex Is The Most Common In Identical Twins?

Identical twins can be born as either boys (XY) or girls (XX). They are always the same sex, but it's more common for them to be girls (XX) than boys (XY).

What Is A "Mirror" Twin?

The phrase "mirror twin" describes a unique category of identical, or monozygotic, twin pair. These twins look like they're looking in a mirror because their special traits, like birthmarks, dominant hands, or other features, are on opposite sides.

Do Identical Twins Have The Same Dental Records?

Much like your fingerprint, your teeth are entirely unique to you. Dental records can even help identify human remains because even identical twins possess different teeth. As a side note, your tongue has its own distinct print that is also unlike anyone else's.

Do Identical Twins Have The Same Blood Type?

Identical twins have the same blood type, although we have seen an extremely rare exception. In contrast, fraternal twins can either have the same blood type or different blood types.

Do Identical Twins Have The Same Fingerprints?

No. Identical twins, who share the same DNA and often look very similar, will have slightly different fingerprints. Genetic and environmental factors combine during their development in the womb to form fingerprints.

Which Parent Is Genetically Responsible For Twins?

A limited number of genes are undeniably associated with hyper-ovulation. This implies that the overall genetics from the mother's side play a role in the likelihood of having fraternal twins. However, on the father's side, there's no evidence that it increases the likelihood of having twins.

What Causes An Egg To Split Into Twins?

Identical twins originate from a single egg fertilized by one sperm at the very start of development. Then, when the zygote is just a tiny cluster of cells, it splits into two. At this early stage, both babies have exactly the same genetic material.

In cases where a mother receives fertility assistance, identical twins can still happen. Placing one of the fertilized eggs back into the uterus, followed by division, leads to the formation of identical twins.

My Twins Had Separate Placentas. Doesn’t That Mean They Are Fraternal?

Twins with separate placentas aren't always fraternal. To know for sure, you need a twin zygosity DNA test.

Before DNA testing became common, doctors and parents believed that if twins had their own amniotic sacs and placentas, they must be fraternal.

Fraternal twins begin when two different sperm fertilize two separate eggs. These fertilized eggs grow separately in their own 'in-utero homes' and can be girl/girl, boy/boy, or boy/girl.

Identical twins begin when one fertilized egg splits into two. This usually occurs around days 4 or 5, after the placenta and amniotic sac have already started forming. However, if the fertilized egg splits before the placenta and amniotic sac usually begin forming for identical twins, like around days 2 or 3, each zygote grows its own sac and placenta.

So, what might seem like fraternal twins to a doctor may actually be a pair of identical twins.

How Much DNA Does The Child Of An Identical Twin Share With Their Parent’s Twin?

A child of an identical twin will share the same amount of DNA with the identical twin sibling of their parent as they do with their parent. This is because identical twins have the same genetic makeup, so the child's DNA will be as genetically similar to their parent's identical twin as it is to their own parent. While it may seem unusual, genetically speaking, the child's parent's identical twin is indeed as closely related as a biological parent in terms of shared DNA.

What Are The Common Myths About Twin Zygosity?

Studies show that medical professionals often influenced parents or twins with mistaken zygosity beliefs through incorrect advice. Their own inaccurate assumptions also played a role in shaping their beliefs. Myths associated with twin zygosity include:

- All same-sex twins are identical: This is not true because same-sex twins can be either identical or fraternal. To be certain, determine zygosity through DNA testing.
- All twins with separate placentas are fraternal: While separate placentas often indicate fraternal twins, some identical twins can also have separate placentas, making it an unreliable indicator of zygosity.
- All IVF-conceived twins are fraternal: IVF-conceived twins can be either fraternal or identical, just like naturally conceived twins. Zygosity testing is the only way to confirm.
- Identical twins must look exactly alike: Identical twins may look very similar, but they can still have differences in appearance due to factors like environmental influences and random genetic variations. Looking identical is not a requirement for them to be considered identical twins.

Step-By-Step Directions

The mouth (buccal) swabs are packaged in sterile packaging. You will have two packets. Each packet contains TWO swabs. You will use all 4 swabs for each person.

Step 1: Complete the information on the DNA collection envelopes.

The names listed should be the same as you put on your order form. There will be one collection envelope for each person whose DNA is being collected.

Step 2: Open the paper packaging and remove the swabs.

Please be careful to handle the swabs on the long handle (the non-cotton end) only. DO NOT, at any time, touch the cotton end with your hands or fingers.

Step 3: With clean dry hands, collect cheek cells by rolling the tip of the sample collection swab firmly on the inside of the right cheek and under the tongue for 20-30 seconds.

Be sure to roll the swab over the entire inner cheek surface. Repeat this process for the same individual with the second swab. You should use two swabs on the inside of the right cheek and two swabs on the inside of the left cheek. Repeat the process for every individual being tested using a different set of swabs and envelope for each person.

Step 4: The mouth swabs should be dry before putting them into the collection envelope.

The best way of doing this without risking contamination is to place them in an upright position in a clean dry glass. Do not put more than one person's DNA samples into a glass at a time. The DNA samples of each person must never touch each other. Once they are dry, place them back into the correct envelopes.

Step 5: Place all of the swab envelopes, plus and any included forms that you have completed, into the large pre-paid FedEx return envelope.

Then simply return them to a FedEx office or call FedEx to pick it up at a time that fits your schedule.

Your DNA test results will be easy to read and understand. We will also provide you with our "Understanding Your DNA Results" booklet.

We are providing examples of Twin Zygosity Test reports below to give you an idea of what the results you receive will look like. 

Zygosity tests always have only one of two results, and they are guaranteed to be 100% accurate. The results will either indicate that the individuals tested are monozygostic or excluded from being monozygostic.

The first example report shows a 0% probability of monozygosity. This means that the siblings testing are NOT identical twins, and are "fraternal" twins.

Twin Zygosity Exclusion 

This second example show that the twins testing have every genetic marker tested the same, which makes them "identical" twins.

Twin Zygosity Inclusion

Once you get your DNA report back, if you have questions, we are happy to provide you with help if needed. 

Our testing is the next step in your journey to truth about your family!

REAL CLIENT REVIEWS    You can read more of our firsthand reviews from customers who have done their DNA testing through our company by clicking on CLIENT REVIEWS. We take pride in delivering a top-notch 5-star customer experience. Reach out to us with any questions. We look forward to helping you on your journey to truth through DNA.

Happy Customer!

Rated 5.0 out of 5
December 4, 2023

I could not be happier with the service they provided and the results I got!

Jennifer R


Rated 5.0 out of 5
August 6, 2023

Could Not Have Been Easier

Jennifer O


Rated 5.0 out of 5
July 19, 2023

Fantastically fast results! Would definitely recommend!

Natalie G

Recommended for DNA tests

Rated 5.0 out of 5
June 6, 2023

Love the ease of ordering the test! The results were delivered to me quickly, privately, and in a secure manner. This could not have been easier.

Heather L

Good Experience

Rated 5.0 out of 5
December 15, 2022

Fast, professional and they value you your privacy. Instructions are self explanatory and easy.

Amanda D