In a tiny new office in fashionable midtown Manhattan, Caspar W. Weinberger Jr. began setting up shop last week for the International Communication Agency.

Weinberger is establishing a new "public liaison's office" in New York, which will serve as an extension of the large public and congressional liaison office maintained by the agency in Washington. Weinberger's task, he explains, is to tell the story of America's overseas information apparatus to the American press and taxpayers at home.

Weinberger is not the Cabinet officer whose name is now familiar to newspaper readers. He is the secretary of defense's 34-year-old son. Caspar Jr. was hired for the newly created job -- with a GS15 rank, salary range of $44,500 to $50,112 -- by ICA director Charles Wick, a longtime friend of Weinberger pere. Young Weinberger, according to Wick, has "a dazzling mind . . . and towering IQ, one of the top guys at Harvard."

Before Wick discovered him, Weinberger Jr. was working as an independent public relations consultant and, before that, for the Bank of America in the government relations department.

Weinberger Jr. is one of several relatives of Reagan administration officials who have followed their more prominent kin into the government. While some bureaucrats grumble about Republican nepotism, the fact is that the federal government is often a family affair when new administrations arrive, Democratic and Republican. President John F. Kennedy appointed his brother Robert as attorney general and President Jimmy Carter hired his cousin Hugh A. Carter Jr. as special assistant to the president for administration.

In the last two decades, there have been sporadic efforts -- to little avail -- to control the hiring of relatives in the executive branch or on Capitol Hill, where members' wives and children sometimes show up on the payrolls of their colleagues.

And, there have even been some notable examples of restraint. In 1969, Edward C. Nixon turned down a $30,000 government job in Alaska because the then-president's younger brother "didn't want to put the president in an awkward position," White House assistant John D. Ehrlichman said at the time.

The statute that regulates nepotism in the federal bureaucracy prohibits an existing government official from hiring a relative "in the agency he is serving or over which he exercises jurisdiction or control." Otherwise, nothing bars a relative from being hired in another department or in the same department under a different supervisor.

Thus Vice President George Bush's cousin, John M. Walker, can serve as assistant treasury secretary. White House policy adviser Martin Anderson's wife, Annelise, can work as an economist for the Office of Management and Budget. Sen. John G. Tower's wife can be nominated to be the director of the Institute for Museum Services in the Department of Education. Navy Secretary John F. Lehman Jr.'s two brothers, Christopher and Joseph, can serve in the State Department and the U.S Arms Control and Disarmament Agency, respectively.

In an interview, young Weinberger acknowledged that he is a little apprehensive about dealing with the press. "I have a small security problem," he explained and asked that the precise location of his New York office not be revealed.

"This country's defense policy is not very popular in some quarters," he said.

Young Weinberger said he has received no threats since his father became secretary of defense, but believes there is a real risk. As a youngster, he recalled, he was answering the doorbell of the Weinberger home in Sacramento after his father had introduced legislation in the California state assembly to control "cancer quackery."

"When I got about four steps from the door, someone threw a brick through it," Weinberger said.

A day after the interview, the ICA put out a press release on Weinberger's appointment with the exact address and room number of his office on West 57th Street.

The defense secretary's son said he does not take any question of nepotism seriously and considers that his Harvard degree, his three-year stint as a producer for a San Francisco television station in the late 1960s and his work in Ronald Reagan's gubernatorial press office in California qualify him for his job beyond any question.

However, he discussed the question with his father. "I suggested that it might be something that would generate a fair amount of interest and, perhaps, a negative reaction," Weinberger Jr. said. His father dismissed the problem, telling his son that "we need good people in government . . . and you're a qualified person."

The son agreed: "Personally, I think it's pretty silly."

At the end of the interview, Weinberger Jr. said that his new office has presented a host of logistical difficulties to him, including the high cost of living in New York City and the personal expense of moving his two pet dogs from San Francisco. One of the dogs, described by Weinberger Jr. as an 11-year-old "mutt," died of an apparent heart attack in transit.

Bob Flynn, an official of the office of government ethics at the Office of Personnel Management, said there have been few requests for information on nepotism policy by the new Reagan department heads. "A lot of agencies have their own regulations," said Flynn.

Flynn said his office handled one inquiry during the Reagan transition involving one brother of Navy Secretary Lehman. The brother, Christopher, wanted to work in the Pentagon, Flynn said, but was told the regulations would prohibit it. That ruling was reversed by the White House, but Christopher Lehman, who has extensive academic credentials in military and strategic affairs, decided instead to take a job as director of the State Department's office of strategic nuclear policy.

Staff writer Karen DeYoung contributed to this article.