About forty years ago, Peter Rosbeck visited Martha’s Vineyard for a day with Karen Sullivan, his girlfriend at the time, and her parents. While the rest of the party spent their time on the beach and sightseeing, Peter sat in a real estate office in Vineyard Haven, picking the brain of an agent. “I really can’t tell you why,” Peter says, “because I really didn’t have money to afford things at that time, but I was just enamored with the whole idea of real estate and what I’d seen of the Island.” Karen later became his wife, and that casual real-estate mentoring became the beginning of the Rosbeck family business.

Or, to be more precise – businesses.

Peter and his sons, Peter Jr. and Ted, own and operate several firms on-Island and off, including Rosbeck Builders Corporation and Island Pools and Spas. The senior Peter, under the aegis of Rosbeck Realty Corporation, is responsible for more than ten real-estate developments on the Island, including Island Grove, Major’s Cove, and Bold Meadow in Edgartown; Meadowview Farms, Bayes Hill, and Hidden Cove in Oak Bluffs; and South Vine and Deep Bottom Pond in West Tisbury. His son and namesake is the “front-lines” guy, involved in the building of custom homes, while Ted handles the finances and paperwork. Karen helps to decorate the model homes, and two daughters, Heather and Daenya, act as “unofficial ambassadors,” according to their mom.

Peter Sr. cut his teeth on real-estate development while helping to revitalize the town of Quechee, Vermont, in the late 1960s and early 1970s. While raising their children in Newton, the couple kept a weekend and summer home on the Island, where Peter Sr. built most of his businesses. Besides on the Island, he’s been involved in developments in Florida and on Nantucket, the Cape, and the South Shore. The family also owns a horse farm in Ocala, Florida.

Peter Jr. learned the trade almost literally at his father’s knee. According to Karen, “Young Pete followed him from the time he was little. If his father was going to work, he wanted to go with him. He would sit for hours in the truck while [Peter Sr.] was talking to people.” Through high school and college, Peter Jr. would spend summers and weekends working on job sites. In 1991, Peter Jr. graduated from Boston College with a degree in economics and immediately joined the family business.

Ted took a circuitous route to the job he holds now. He also spent summers working on Island construction sites during high school and college, but after graduating from the Boston College School of Management in 1999, he took his business degree on the road, managing restaurants and investing his energies in an Internet start-up in California. When Karen’s brother-in-law Bob Keim retired from the family business a few years ago, the Peters lured Ted back to the Island to fill Bob’s position with promises of fishing and boating – his favorite down-time endeavors.

Although the Rosbecks agree that there are occasional “head-butts,” a conversation with any one of them shows how much they admire and josh with each other.

“Obviously, working with family isn’t always the easiest,” Ted says, “but it’s been working out great.” He smiles. “We’re a very close family.”

Critics say the family has contributed to the suburbanization of the Island. “There are a lot of developers that go in and just throw in roads and don’t really put much effort” into the quality or finish of the homes, says Peter Jr. “Really, what my father and myself did is we controlled the building as much as we could because we cared about the outcome.” And unlike other developers who came in, made their money, and left, the Rosbecks stayed and have actually lived in many of the developments they’ve built on the Island.

Wait. Many of them?

“We’d use our house as kind of a show house that [prospective buyers] could go through,” Karen says. If they didn’t want to wait for a house to be built, the family would sell its own. Karen has returned from off-Island and found her husband and sons acting strangely. “I would say, ‘Peter, did you sell my house?’ They would say ‘Mom [or Karen], I can build you a better one.’”