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National Twins Day: Why it Matters and How to Celebrate

National Twins Day, celebrated each year on the first weekend of August, is an event that recognizes the special bond between twins. The day is dedicated to celebrating their deep connection and acknowledging the challenges twins and their families face.

National Twin Day goes beyond mere festivity; it actively supports twin research and acknowledges their valuable contributions to society. 

For instance, the insights gained from twin studies have been instrumental in understanding the interplay between genetics and environment. Furthermore, by raising awareness about the distinctive aspects of twin life, this day fosters inclusivity and empathy, ultimately helping to create a more compassionate society that values each person's individuality.

Featured in: August - Awareness Months, Days & Observances.

National Twin Day History and Background

The story of National Twin Day began in 1976 when the Twins Days Festival Committee in Twinsburg, Ohio, decided to celebrate the unique bond shared by twins. 

Twinsburg was the ideal location for such an event, as it was named after its founders, identical twins Moses and Aaron Wilcox. In August 1976, the first Twins Days Festival took place, attracting 37 sets of twins who enjoyed a weekend filled with camaraderie and twin-centric activities.

National Twin Day has come a long way since its modest beginnings. The Twinsburg event's popularity soared, earning it a spot in the Guinness Book of World Records in 1994 as the "World's Largest Annual Gathering of Twins." 

Its peak attendance was recorded in 1999 when an astounding 3,000 sets of twins, triplets, and other multiples from around the globe joined the celebration. 

The gathering often includes individuals from the scientific field, who take advantage of the abundance of identical and fraternal twins in attendance to carry out voluntary studies. These studies aim to establish whether human traits have a genetic or non-genetic origin.

Read more: Twins Days Festival (official website)

From an annual gathering to a worldwide observance

This incredible growth captured the spirit of the twin community and inspired similar celebrations in countries like Australia and the United Kingdom3.

National Twin Day evolved into more than just a gathering as the years passed. It now plays a vital role in raising awareness about twin-specific health issues, such as Twin-to-Twin Transfusion Syndrome (TTTS)4

By supporting medical research funding and fostering a sense of unity among twins and their families, National Twin Day has become a significant annual event for the twin community worldwide, creating lasting memories and changing lives for the better.

Is National Twin Day in December or August?

twin brothers
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We've found a range of sources citing December 18th as National Twins Day. Accordingly, some people do observe it on this day in December.

However, as it is not an official holiday, our research suggests the history of National Twins Day is closely linked with the Twins Day Festival in Ohio (as above). Therefore, the August date is most likely the more popular observance. However, you can also celebrate them both!

The Cause and Its Challenges

National Twin Day also serves as a call to action for greater understanding and support systems tailored to the needs of multiple birth families. By shining a light on the specific issues these families face, this awareness day emphasizes the importance of addressing their challenges and paves the way for improved resources and assistance.

Throughout their lives, twins encounter a variety of social, educational, and health-related hurdles. One significant issue is identity confusion, with identical twins often seen as a single unit rather than separate individuals. Moreover, academic comparisons between twins can create unnecessary pressure, affecting their self-esteem.

The families of twins face challenges, too, both financially and emotionally. 

Raising twins can be expensive, often requiring double the resources, which can strain household budgets. 

On top of that, twins are at a higher risk for specific health issues, such as premature birth and low birth weight. A study found that these factors make twins more likely to experience long-term health complications6. National Twin Day aims to create a more supportive and inclusive environment for twins and their families by raising awareness of these challenges.

10 Interesting Facts About Twins

Adult female twins
Photo by Italo Paiva
  1. The birth rate for twins has increased by over 75% since 1980. 
  2. People of African descent are more likely to conceive twins, while Asian and Native Americans have lower rates.
  3. About 33 in every 1,000 births in the United States are twins.
  4. Twins can be identical (monozygotic), meaning they have come from a single fertilized egg, or fraternal (dizygotic), where two different eggs are fertilized. About 1/3 of all twins in the U.S. are identical.
  5. While typically twins share the same birthday, there have been instances where twins were born on different days and, in some extreme cases, different years due to being born around midnight on New Year's Eve.
  6. Massachusetts has the highest twin birth rate, with 4.5% of births being twins, as per CDC’s 2018 data.
  7. Twins share remarkably similar DNA, but they are not identical matches. Scientists have recently discovered that identical twins have slight genetic differences known as Single Nucleotide Polymorphisms (SNPs)2.
  8. According to a Swedish study, the mortality rate is lower for mothers of twins than for mothers of singletons1.
  9. Even before birth, twins interact with each other in the womb. Ultrasonography studies have shown that twin fetuses begin interacting as early as the 14th week of gestation. At this stage, they can touch not only their own body but also reach out and touch their co-twin, spending up to 30% of their time in physical contact.
  10. Developing a private language known as idioglossia is a fascinating aspect of twin communication. Research indicates that up to 40% of twins develop their own language5, usually a mix of reversed words, scrambled syntax, and made-up vocabulary understood only by the twins. This typically fades away as they age and learn the standard language spoken in their environment.

Efforts and Initiatives

While community events are notable, nonprofit organizations are crucial in raising awareness about twins and multiple births. Twins Research Australia and Twins UK have made significant strides in understanding the world of twins through their research. These organizations provide resources, support, and events for families and healthcare professionals.

Collaboration is key when it comes to improving the lives of twins and their families. The International Society for Twin Studies (ISTS) has been instrumental in fostering collaboration among researchers and professionals in twin studies. 

They work together to promote research, education, and a better understanding of the twin experience. Events like World Twins Day and the Twins of Faith Conference encourage the international community to celebrate twins' uniqueness while tackling the challenges they encounter.

How to Get Involved and Support the Cause

Looking to celebrate National Twins Day? A fantastic way to dive in is by joining local events and activities held in honor of this unique celebration. 

Keep an eye out for parades, meet-ups, or picnics in your area – these gatherings are perfect for sharing your best twin memories and stories and connecting with others who cherish the twin experience. You can also organize your own twin party, invite other twins for double the fun or simply celebrate with friends and family. 

Whether you’re a twin or not, you can snap some photos of all the twins you know and share them on social media using #NationalTwinDay to raise awareness and discover others passionate about the cause.

Knowledge is power; the more you know about the twin community, the better you'll be able to support them. Did you know that there's a "Twin-Language" phenomenon? Share intriguing findings with friends, family, and coworkers, sparking conversations and spreading awareness about the extraordinary aspects of twin life.

Ready to make a lasting impact? Consider lending your time or resources to organizations that advocate for twins and their families. Look for hospitals, schools, or community centers hosting twin-centric events or workshops – they often need helping hands. 

What’s the difference between fraternal and identical twins?

2 young twin brothers
Photo by Eduardo Barrios on Unsplash

Identical twins develop from a single fertilized egg or zygote that splits into two, resulting in two individuals with almost identical genetic characteristics. While the reason the fertilized egg splits is not entirely known, it generally takes place during the first two weeks post-conception. 

Fraternal twins develop when two separate eggs are fertilized by two different sperm cells. This results in two embryos that share the womb but have separate placenta and amniotic sacs. Also known as dizygotic twins, fraternal twins share about 50% of their genetic material, just like any other siblings, and can be of the same or different genders.


National Twin Day is a powerful reminder of twins' exceptional role in our society, enriching its diversity. 

When we take a moment to appreciate the remarkable connection shared by twins, we can better recognize the contribution of twin lives to our communities. As a result, we can actively support causes that champion their well-being.

National Twins Day FAQs

1. When is National Twins Day Celebrated?

National Twin Day is celebrated on the first weekend of August every year.

2. What is the purpose of National Twin Day?

National Twin Day honors twins' unique bond and raises awareness about twins' challenges.

3. What challenges do twins face?

Twins face challenges like identity issues, competition, comparison, and health concerns like Twin-to-Twin Transfusion Syndrome (TTTS).

4. How can I celebrate National Twin Day?

You can celebrate National Twin Day by spending time with your twin, organizing a twin-related event, or sharing your twin stories on social media using the hashtag #NationalTwinDay.

5. Are there any organizations dedicated to supporting twins?

Yes, organizations like the National Organization of Mothers of Twins Clubs (NOMOTC), Twins Research Australia, and the Twins and Multiple Births Association (TAMBA) offer support and resources for twins and their families.


Koster A, Bosma H, Kempen GIJM, et al. Socioeconomic inequalities in mobility decline in chronic disease groups (asthma/COPD, heart disease, diabetes mellitus, low back pain): only a minor role for disease severity and comorbidity. Journal of Epidemiology & Community Health 2004;58:862-869.


Kantor, V., Mo, L., DiNonno, W., Howard, K., Palsuledesai, C. C., Parmar, S., Chithiwala, Z., Jelsema, R., Xu, W., & Hedriana, H. L. (2022). Positive predictive value of a single nucleotide polymorphism (SNP)-based NIPT for aneuploidy in twins: Experience from clinical practicePrenatal diagnosis42(13), 1587–1593.


Segal N. L. (2003). Between twins; research summaries; in the real worldTwin research : the official journal of the International Society for Twin Studies6(6), 498–501.


Christian Bamberg, Kurt Hecher, Update on twin-to-twin transfusion syndrome, Best Practice & Research Clinical Obstetrics & Gynaecology, Volume 58, 2019, Pages 55-65, ISSN 1521-6934,


Bakker P. (1987). Autonomous languages of twinsActa geneticae medicae et gemellologiae36(2), 233–238.


S. Hari Kumar, K. V., & Modi, K. D. (2014). Twins and endocrinology. Indian Journal of Endocrinology and Metabolism, 18(Suppl 1), S48.

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