What These Identical Twins, One of Whom Is Over a Foot Taller, Look like at 25 — Photos from Their Childhood and Now

Identical twins Sienna and Sierra Bernal were born with very different birth weights. Sierra weighed over 4 pounds, while Sienna was just under 1 pound 8 ounces. Doctors initially linked Sienna’s small size to several health complications.

At six, Sienna was diagnosed with primordial dwarfism, a rare condition affecting fewer than 200 people worldwide, with her specific type still unclassified. Now 25, the sisters have embraced their differences and turned their unique story into a source of inspiration.

Born Against the Odds

Sienna and Sierra entered the world prematurely on December 22, 1998, and their differences were apparent from the start. The twins were born with a weight difference of over 3 lbs. Their mother, Chrissy Bernal, recalled the whirlwind of emotions upon learning she was carrying twins.

“[The doctors] said, ‘So, you’re having twins, but you need to quickly get over that because we need to talk about baby B,’” she explained. The focus quickly shifted to Sienna, who was noticeably smaller and faced a series of health complications.

Before Sienna was born, a sonogram revealed she had a hole in her heart and signs of Dandy-Walker Syndrome, a rare congenital condition that affects brain development.

After her birth, doctors initially attributed her small size to these complications, coupled with her underdeveloped lungs and recurring pneumonia. However, these assumptions didn’t fully account for her drastically slower growth compared to Sierra.

The Bernal twins’ case is an extraordinary example of discordant twinning, a rare phenomenon where identical twins display significant differences in size or growth. Despite originating from the same fertilized egg, their genetic makeup diverged after the egg split.

In November 2022, Sienna stood at 4 feet 4 inches and weighed 50 pounds, while Sierra measured 5 feet 7 inches tall and weighed 98 pounds — giving them a height discrepancy of over a foot and a weight difference of nearly 50 pounds.

According to medical definitions, this qualifies as twin growth discordance, where the smaller twin’s estimated fetal weight falls below the 10th percentile. Their unique case has even earned them a Guinness World Record for the greatest height difference between identical twins.

Chrissy explained the genetic mystery behind their differences, stating, “Because Sienna’s diagnoses are mutations, her genes mutated after the egg split. That’s how they’re so different even though they’re ‘identical’ twins.”

Their physical differences may be striking, but Sienna and Sierra’s relationship has always been rooted in their experience and unbreakable connection.

Sisterly Bond Despite Differences

Growing up, the twins’ bond was shaped by Sienna’s unique medical needs, which often placed Sierra in a “big sister” role rather than an equal twin dynamic. Their family members often marvel at their differences and uncanny similarities.

Their stepfather, Joey Bernal, shared that while Sierra can deliver humor with intention, Sienna’s unintentional remarks often leave everyone laughing the hardest. “They’re both really, ridiculously silly and very funny in their own right,” Joey said.

The sisters themselves rarely focus on their differences, instead leaning into their experiences. Through the years, their relationship has been a source of strength for both. Sienna credits Sierra with helping her navigate emotional challenges.

“[Sierra] has helped me with my emotions more and helping me control them. When I was younger, my emotions would explode because I didn’t know how to control them, but as I’ve gotten older, I’ve learned how to control my anger,” she shared.

Sierra, in turn, acknowledges how growing up alongside Sienna has influenced her perspective and growth. Their twin bond often manifests in uncanny ways. Their stepfather, Joey, recalled a moment when the twins, sleeping in separate rooms, mimicked each other’s movements.

“[Sienna] always wanted to be more like her sister, and she always worked harder to get to that level,” Joey added, reflecting on the mutual admiration between the two.

Despite living separate lives now — Sienna in Texas and Sierra in Nashville — the twins continue to maintain a strong emotional connection.

Making Their Mark

The Bernal twins have embraced their differences to live meaningful and impactful lives. Sienna has become a passionate advocate for individuals with restricted growth, dedicating her time to causes like the Equal Restroom Access for Little People Movement.

Alongside her mother, Chrissy, she challenges public spaces to become more inclusive. Her advocacy stems from personal experiences, and her efforts showcase her determination to make the world a better place for others like her.

Meanwhile, Sierra has pursued her dreams in the music industry. An aspiring country singer, she is a member of the Country Music Association and has made strides toward a successful career in Nashville. Her experiences growing up with Sienna have shaped not only her worldview but also her music.

“Having Sienna as my sister has made me grow up faster than I think I would have naturally,” Sierra shared. The twins find it amusing to be recognized by Guinness World Records twice just for being themselves. Sienna admitted, “I think it’s funny. We are just living our lives.”

Their achievements show their individuality, but humor, connection, and unwavering support are at the core of their lives as sisters. These qualities stand out even more in their daily interactions and how the public sees them.

Everyday Life and Public Perception

Living with such visible differences has made Sienna and Sierra stand out wherever they go, often leading to curious — and sometimes humorous — public interactions. Sienna, who is often mistaken for being much younger, once shared, “When we go to bars, people think I’m eight even though I’m 23. It’s really funny.”

Sienna’s short stature also means she often needs to get creative in her daily life. From reaching for items in high places to navigating spaces not built with accessibility in mind, she finds inventive ways to adapt. Fortunately, she always has Sierra to lend a helping hand when needed.

“Sometimes when we go out in public, people will think she’s my mom and not my twin because I’m so short,” Sienna joked, offering another glimpse of the sisters’ lighthearted outlook. “Other than that, I live a normal life.”

Navigating public perceptions with humor is just one aspect of their lives. Behind the smiles and witty remarks, Sienna and Sierra have faced profound challenges, turning them into opportunities for growth and triumph.