• Ben Sanderson always knew he was conceived using a sperm donor
• When he turned 18 he began looking for his donor and potential siblings
• Eventually, Sanderson’s learned he had 40 siblings, of which he is the youngest
• He’s since gotten in touch with his siblings, and even met a few of them in person

Ben Sanderson always knew he was conceived using a sperm donor. Growing up, his mom told him that when he turned 18, he could start searching for his biological father and potential siblings if he wished.

So, one Sunday last May, feeling both bored and curious, Sanderson, a theater student at Indiana University, decided it was the perfect time to explore his paternal family history.

Despite being across the country from his home in Los Angeles for a theater role in Indiana, he called his mom, who eagerly joined him in the search. Together, they logged into the sperm bank’s website, which featured a sibling registry and chat room where siblings of the same donor could leave messages to potentially connect with one another.

When Sanderson, who had grown up only with his mom and pets, opened the chat, he stumbled upon a message from 11 years ago.

“It basically said, ‘Hi, my name is [name], and I’m your half-sister…'” Sanderson recalls to PEOPLE exclusively. He was surprised to discover that the message was from a girl who also had a full sister conceived using the same donor.

“I was like, ‘Oh my God, I have two sisters!’ She had left an email address from when she was a teenager,” Sanderson recalls.

He decided to reach out, writing, “Hi, my name is Ben. I’m a donor child with the same donor number as you. I’m 18 years old and just logged onto the sibling registry for the first time today. I saw your message and would love to connect. Please let me know if you see this,” leaving his Instagram handle.

To his surprise, the next day, May 31, 2023, Sanderson received a direct message from her.

“I was freaking out,” he says. “I was with my friends, and they were freaking out too. She said, ‘Hi, this is [name]. I got your email. I’m so happy that you reached out. I’d love to get to know you.’”

Excited, Sanderson began talking with his newfound sister. He also noticed many new followers on Instagram who appeared to be mutual friends of hers. At first, he thought they were just her friends, but soon he realized they resembled him, too.

That’s when another sister reached out via DM, introducing herself and offering to add him to a group chat called “Future AA Group” with 15 of the siblings. Before she did, she asked him how many siblings he expected there to be.

“I was told I would only have a maximum of 10 siblings,” he recalls replying, based on information from the sperm bank. “No, there are 40 of us!” she responded.

“I was in a restaurant when I found out and realized that I was the youngest of them all,” Sanderson says. “It was the best day ever. I was so excited. I was like, ‘Get out of here!’ That’s the best fun fact ever. No more saying I’m double-jointed.”

After learning the news, he immediately called his mom, who started to cry. “She told me she had enough fried chicken for that,” he says.

Since then, Sanderson, who refers to his siblings by a numbering system to protect their privacy, has started learning more about them. He’s shared his discoveries on TikTok, where his first video explaining his discovery has garnered more than 8.5 million views.

@thebensanderson

#putafingerdown #storytime #donorconceived #donorconception

♬ original sound – BEN SANDERSON

Among his 17 older sisters and 23 older brothers, including four sets of twins, Sanderson quickly noticed that all his siblings are animal lovers and none of them can play a musical instrument.

He’s also learned more about each of them through a spreadsheet the siblings created, which includes details such as their zodiac signs, college majors, whether they are vegetarian, and at what age they discovered they were donor-conceived.

“We respect each other’s boundaries,” he says. “Some of us act like we were siblings from day one, while others treat each other more like acquaintances.”

“I have a lot of siblings that I’ve never talked to because they don’t want a relationship,” he adds. “Especially with the rise of 23andMe and Ancestry, straight parents who lied to their kids about being donor-conceived are now finding out.”

“I think the advantage I had over my siblings is that the 40 of them found each other before I did,” he continues. “One of my sisters mentioned that she only knew of seven siblings at first, then 12, then 17. She would wake up every day wondering, ‘Am I going to get another sibling today?’ “

Shortly after discovering he had 40 siblings, Sanderson traveled to New York City on Aug. 1, 2023, to meet a few of them in person. The first sibling he met was Sister 1, the eldest of the group, who had initially reached out to him.

They met at a coffee shop and then attended a Broadway show together, bonding over their shared love for the arts.

“I arrived early and was scanning the room, thinking, ‘Is my sister here?’ ” he recalls. “Then she walked in, and I immediately knew it was her. I gave her the biggest hug ever. It felt like making a new friend.”

Afterward, Sanderson met Brother 31, who joined him for two more Broadway shows. He also met Sister 5 and Sister 33. Meeting a brother was particularly exciting for Sanderson, as he had never been very close with any male relatives, he says.

Upon returning to Los Angeles, Sanderson met up with Sister 9 from San Diego. They enjoyed lunch and a visit to Santa Monica Pier, and have since met up again. Recently, Sister 9 invited him to her wedding.

“You know what it’s like to have 40 siblings? It’s overwhelming,” Sanderson says. “That’s a lot of happy birthdays, a lot of Merry Christmases and a lot of weddings. And as the youngest, it also means receiving 40 phone calls if a sibling passes away. It’s a huge network of relationships, but I love it, and so do my siblings.”

@thebensanderson

Replying to @Vanessa Mhlom #donorconceived #donorconception #story #storytime

♬ original sound – BEN SANDERSON

Throughout his journey, Sanderson has also connected with his donor, whom he refers to as his dad, though many of his siblings don’t share the same view.

In February, Sanderson sent his first email to the donor, introducing himself and sharing a bit about his life — his love for theater, his height of 6’5″ and his inability to grow a beard. He included five photos of himself in the email. A month later, as Sanderson was heading to a class, he received a response.

“He was thrilled to learn that I’m an actor,” Sanderson recalls. “He used the sun and the moon as metaphors for our relationship, saying that even though we’re far apart, it’s still an important connection in the galaxy.”

“He essentially wanted to match the energy I was giving him,” Sanderson adds, noting that since then, they have continued to exchange emails back and forth.

Looking back, Sanderson says he’s glad he waited until he turned 18 to reach out to his donor family. In fact, he recommends that every donor-conceived person also wait until they are 18 before searching for their siblings or their donor.

“My mom and I were on the same page about this,” he says. “I was an adult when I found them, so I could make my own decisions and set my own boundaries. I had 18 years of knowing that I wanted to find them. I think trying to search as a child would have been overwhelming.”

Although the initial discovery is now behind him, Sanderson remains excited about the possibility of more siblings coming forward. Until then, he plans to continue strengthening his relationships with the siblings he’s found.

“I’d be really upset if someone younger than me shows up and I’m no longer the baby of the group,” he jokes. “If they’re older, that’s fine. But if they’re younger, I’m going to be so sassy about it. I want to be the youngest!”