COEUR d’ALENE — Two half-sisters, two years apart, have been reunited.

A substance found in almost all living things called deoxyribonucleic acid — that is, DNA — brought them together.

Robin Cooper-Anthony, a Coeur d’Alene real-estate agent, and Lynn Dilling, a bank manager in Troutdale, Ore., received 23andMe kits as gifts. The company uses genetic samples from saliva to reveal one’s genetic traits and ancestry. It also can provide a list of other customers who have been found to have similar genetic profiles.

Cooper-Anthony’s husband, Steve, gave her a test kit last Christmas. As she unwrapped it, she joked that she’d always wanted a sister.

But the kit went untouched for weeks, complicit in a secret the two women shared inside their cells. Cooper-Anthony wound up sending her sample sometime in January.

She did not know — and couldn’t have known — that her half-sister was about to do the same thing.

Dilling’s daughters surprised her with a 23andMe kit for Mother’s Day.

“I was adopted at birth,” she said, “and I’ve always been very curious about my background,”

Dilling received an email a few weeks later that said her results were completed.

“It was Father’s Day,” Dilling said. “I remember because I waited for my daughter to get to my house to open the results.”

With her daughter by her side, Dilling learned that her DNA matched Robin Cooper-Anthony. The results were close enough that the two women could be half-siblings.

“I was surprised,” Dilling said. “I knew it was a possibility that I had siblings, but until you actually see the DNA match — I was a little bit in shock.”

And apprehension. She waited to reach out to Cooper-Anthony.

“I didn’t want to upset anyone,” Dilling said. “That was my worst fear.”

Aug. 12 was just another day for Cooper-Anthony. She went to Cold Stone Creamery with her husband. As her husband parked the car, she checked her email while she waited outside the ice cream shop. She saw a message from 23andMe.

It wasn’t from the company.

It was from another one of its customers.

“Hi, Robin,” the note said. “My name is Lynn. I think I’m your sister.”

Cooper-Anthony was too stunned to move out of the doorway as other customers shuffled around her. Her husband arrived and immediately asked his wife what was wrong. She handed him the phone.

“Oh my gosh,” he blurted. “There’s two of you?”

The sisters met for the first time about a month later.

Dilling and her daughter came to visit Cooper-Anthony and meet Cooper-Anthony’s family.

“I was really excited,” she said. “I always wanted a sister. There was a piece missing, and I didn’t even know it,” Cooper-Anthony said.

“The time I spent with her, I felt very comfortable,” Dilling said. “I felt that I will be part of her family.”

Cooper-Anthony said the two plan to grow close, as sisters should. They’re planning regular visits.

“It was really a joy for me because I didn’t have any sisters,” Cooper-Anthony said. “She’s a blessing. I really cherish her.”