Theo and Jean Laumet grew up hearing stories of their family ties to the man who founded Detroit and inspired the Cadillac brand.

But the story was always something of a family myth.

It was not until the family made a return trip to the city that they came to know the full scope of their roots in Detroit.

Theo, Jean and their father, Francois, are direct descendants of the man considered the founding father of Detroit — Antoine de la Mothe Cadillac. Born Antoine Laumet in the south of France, Cadillac came to what was called New France in 1683, where he became known as an excellent navigator. He set out on an expedition, ending on the Detroit River in 1701.

Detroit was officially founded July 24, 1701.

He and the 100 men who set out with him claimed the land where Fort Pontchartrain du Detroit was established. Cadillac and others founded Ste. Anne's Church two days after the city on July 26, 1701. Ste Anne's Church, which stands at 1000 St. Anne Street in Detroit, is the second-oldest continuously operated parish in the U.S.

More:Detroit’s Ste. Anne Church becomes third in Michigan to receive title of ‘minor basilica’

Establishing new roots

Kimberly Simmons was working a normal Friday evening at the Detroit Shoppe in December 2019 when the Laumet brotherswalked into the store.

The brothers locked in on a Cadillac Boulevard sign the store had on display and asked if they could buy it. Simmons redirected the two to the Renaissance Center's GM store, but the brothers clarified that was not what they were searching for.

"(Then) ding ding ding, the history (bell) went off and I said, ‘Exactly why are you asking me about Cadillac?’ They looked at each other, said a little French, and then said, ‘Well, we are Laumets, Cadillac,’ and the minute they said Cadillac, I went, ‘Oh my god. These are the descendants.' "

With a rough understanding of their family ties to the city, Theo, 24, and Jean, 30, made the trek to see the place founded by their ancestor approximately 11 generations earlier.

"We didn’t tell no one because we were just two tourists enjoying Detroit," Theo said of the December trip. "We came to see a Detroit Pistons game, we won by the way, and we went to just enjoy a Coney dog. We just came to visit the city as two tourists and were just strolling around."

But it shocked Simmons that no one else knew the brothers were there, but the men did not think anyone cared about their family history.

"The first thing I could think of was, ‘Does the mayor know you’re here?’ " she said.

Simmons, outside of working at the Detroit Shoppe, is a local historian and founder of the Detroit River Project. After Simmons met the pair, the men went on their way but promised to make a return trip to see more of the city.

Theo and Jean reached out to Simmons several months later to let her know they were coming back and bringing their father to surprise him. From there, Simmons got to work.

This time, on Friday, the founder's descendants were greeted by a chauffeur driving a Cadillac who took them around the city to see the signs of their family's impact on Detroit.

"When I contacted her (Simmons), I thought we would just grab a coffee together and talk a little bit, maybe (she would) show us the museum and maybe a little tour," Theo said. "I never imagined she would do something that huge."

The tour started at Ste. Anne's Church.

The day included stops at Fort Wayne, the Detroit Public Library, the Detroit Historical Museum, Detroit Institute of Arts and the GM Heritage Center in Warren. The family ties to the city were evident at each location — the bust of Cadillac in the Historical Museum, murals representing their ancestor's arrival and a line of creditcontract with Cadillac's signature.

"That's how everything started, there we go," Theo said of seeing the signature from 1694. "And now we are here in 2020 in one of the most iconic cities in the U.S.A. We have emotion seeing that; it is something that means a lot to us. That is a treasure for us, a family treasure but very valuable for the city of Detroit. This means the world to us."

Detroit City Council President Brenda Jones greeted the family, and recognized their city ties with a Spirit of Detroit award, signed by all Detroit city council members.

Recognizing the city's roots

The family knew about their deep roots in Detroit, but assumed it did not mean much to anyone outside of their bloodline.

In France, family ties to the founding of a city in another country don't carry much weight, Theo said. The family assumed the same was true in the U.S. When the brothers first came to Detroit, though, they were quickly shown how important city history is to the locals.

Simmons said when she first met them and learned their story, two women were listening in as the Laumets shared their family history. Simmons invited them to partake in the conversation.

"It was at that moment we realized how important it was for them because those two ladies asked, ‘Can we take picture with you? We want to show our family,’ " Theo said.

But not everyone understands the city's deep, layered history, Simmons said.

"We know nothing, we don’t recognize what our history is," she said. ... We make cars, and that is just our world and it has been. Everything else we do is just secondary."

After the Laumets' second trip to the city, the family is already looking ahead to the third: a summer trip to speak with children about their family's story at Simmon's Heritage Camp.

"Detroit is a beautiful city," Simmons said. "We need to show it off. Who better to be the champions of Detroit than the founder's descendants?"

Dubbed an honorary Detroiter, Theo said he now understands the full scope of the Cadillac name in Detroit and carries the honor with pride.

"It was a subject in the family but we never thought it would have such an impact in the world," Francois and Theo said as Theo translated for his dad. "We are proud, as I am sure (Detroit) is of how you guys changed, not only Cadillac, but how Detroit changed the car economy and changed the world in its own way. We are very happy our family contributed a little bit. Our ancestor founded the fort of Detroit, but you, Detroit, did everything. You are the ones who made everything happen."

Editor's note: A previous version of this story had incorrect information about the establishment of Ste. Anne's Parish and the number of people on Cadillac's first expedition. According Ste. Anne's Parish, the church was built July 26, 1701. On Cadillac's first expedition to Detroit, 100 men joined him, and 300 families later settled in Detroit. This story has been corrected.

Meredith Spelbring is a news intern with the Detroit Free Press. Reach her at mspelbring@freepress.com or on Twitter @mere0415.