Rondel Holder, who lives in New York and works as a content creator at Essence magazine, was curious about his ethnic background, so he took a home DNA test that he bought from Ancestry. “I always thought of myself as being from Brooklyn, with Grenadian and Jamaican roots,” he said.

But the test results told another story, revealing that much of his ethnicity could be traced to two African countries, Togo and Benin. Mr. Holder said he went online within days of getting the news and booked a trip to Africa for about $3,500.

When he got there, he said he was happy to meet some people his own age. “The locals I connected with were working millennials who liked to go out and have fun, like me,” he said.

Mr. Holder is among the growing number of travelers who take a heritage trip, as they are called, or at least consider one, based on results from at-home DNA tests. They are available through companies such as Ancestry, 23andMe, AfricanAncestry.com and MyHeritage, and typically entail a saliva sample or cheek swab; the results arrive via email or mail within three to six weeks.

Booking.com, one of the world’s largest accommodations booking sites, surveyed 21,500 travelers this summer about their dream trips, and 40 percent reported that they wanted to take or had actually taken a trip based on the results of home DNA tests.

Allegra Lynch, a member of the Travel Leaders Network who lives in Santa Rosa, Calif., said that she sold $1.5 million worth of such trips in 2018, primarily to Europe, compared with $800,000 in 2017. “The rise is 100 percent because of people wanting to go on trips after taking at-home DNA tests,” she said.

An online video created for AeroMexico by the Ogilvy advertising agency last year played on the trend, offering discounts to Americans to fly to Mexico based on the portion of their heritage that a DNA test determined was from Mexico. Amid the debate around border security, the ad has recently gone viral on the Internet. John Raul Forero, the chief creative officer for Ogilvy Latam confirmed in an email that the ad had been created last year for the airline but had no further comment. The DNA promotion is no longer valid, according to Paula Santiago, a spokeswoman for the agency.

Although some genetic experts question the accuracy of such tests to pinpoint geographical ancestry, the molecular genealogist Diahan Southard said that the results are usually on the mark, save for some exceptions. “The ethnicity breakdown you receive from a testing company relies heavily on the people the company is comparing you against,” she said. “If you are from France, but your company hasn’t tested very many French people, they aren’t going to do a very good job with your breakdown.”

Still, accessibility and affordability are helping DNA-based travel take off, according to Sarah Enelow-Snyder, an assistant editor at the travel research company Skift. “You can buy one for less than $100, and it’s a price that has helped propel the popularity of these trips,” she said.

Evita Robinson, the founder of Nomadness Travel Tribe, an online social media group for travelers of color, said that there was noticeable uptick from 2017 to 2018 in its 21,000 or so members talking about home DNA tests and planning trips based on the results. Mr. Holder was among those members.

Ms. Robinson took a test last year that showed she is a mix of African-American and Caucasian and has roots in several countries, including Senegal, South Africa and Ireland. She is traveling to Ireland in May for her first DNA-based trip.

Although DNA-based travel can be poignant for anyone, it may even be more impactful for African-Americans, according to Dr. Gina Paige, the co-founder of AfricanAncestry.com, which specializes in genetic ancestry tracing for people of African descent. “Black people were taken from West and Central Africa to the Americas and the Caribbean, and as a result of that, our identity got lost,” she said. “There are virtually no paper records for us until 1870, which is when the U.S. government started taking census information from us, so trips to Africa to learn more about our roots are often revealing and profound.”

Ancestry is starting a travel division that will include group and private tours. The group portion is a collaboration with EF Go Ahead Tours on a series of trips to Italy, Scotland, Ireland and Germany; they are led by one of Ancestry’s genealogists and start at $3,500 for 11 days.

As part of the group tour package, travelers receive an Ancestry DNA test beforehand and consult with a genealogist who uses their test results, along with historical records, to educate them about their origins. On tour, they follow an itinerary that includes visits to sites heavy on heritage, such as emigration museums and ports where emigrants left for the United States.

Ancestry’s private tours start at $2,000 a day and are created based on a combination of DNA results and research on a client’s family history. “We look at a variety of data, including newspaper archives and church, military, marriage and death records,” said Kyle Betit, a genealogist who heads the company’s travel division. “The itineraries we create take people to the villages where their ancestors lived, and to the churches where they got married.”

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