Lyndra Marshall and Eunice Owens always knew they were cousins, but it wasn’t until more recently that they found out they are “double cousins.”

Marshall’s mother and Owens’ father were siblings. What they didn’t know was that their grandmothers were cousins, too.

Marshall discovered the connection when she was visiting Owens’ mother, Bessie Gross, several years ago.

“I walked in and there was this picture on the mantel, and I said, ‘Aunt Bessie, this looks like my grandmother on my father’s side,’ ”she recalled.

That’s because she was — and she was also Gross’ aunt.

“When you dig deeper it's like, oh my goodness, she’s on this side too,” said Owens. “It's amazing to see how lines cross.”

Marshall and Owens shared the story as part of the Galesville Community Center’s “Family Tree Explosion” event, an event last Sunday that focused on unveiling the genealogical histories of African-American families in the Galesville area.

The gathering was one of dozens of events planned in celebration of the 10th annual Maryland Day, which kicks off the tourist season in the area, said Carol Benson, executive director of the nonprofit Four Rivers Heritage Area.

In Galesville, community members worked with Marshall, who chairs the Maryland Commission of African American History and Culture, on their family trees. Many discovered unexpected links.

“What's fun about it is you start digging up people you don’t realize you were related to,” said Troy Smith, a Bowie resident who grew up in Galesville.

So far, he’s traced his ancestry back to his great-grandparents. And he plans to continue.

“We’re not finished yet,” he said. Owens, who lives in Shady Side, has been able to trace back six generations. She says she got interested in genealogy because she wants to make sure her son knows his history.

“He needs to know who his family is, his legacy,” she said.

As she progresses in her research, Owens makes sure to label old pictures with the names of relatives.

“I knew some of these people, [but] he’ll never know these people,” she said. With the labels, “at least he’ll know some of his family members.”

Marshall, a history buff since childhood, has assembled the longest family tree — “it’ll wrap around this building about six times,” she said. She can track her ancestry back to England in the 1200s on her paternal grandmother’s side, and to Colonial America on her paternal grandfather’s side. Those ancestors arrived as free people, and Marshall was able to find centuries-old wills they wrote. On her mother’s side of the family, she can trace ancestors, who came to the U.S. as slaves, back to the early 1700s.

She’s spent her life immersed in history — from observing and documenting family gatherings as a child to hosting genealogy workshops for local high school students.

Marshall said those projects are greeted with enthusiasm by younger generations.