What was going on when I was born?

The hijacking of a Kuwaiti airliner to Iran this month in which two Americans were killed is but one terrorist episode in a series that reflects new tension in the Middle East, diplomats and Government officials say. According to the diplomats and government officials in Kuwait and elsewhere in the Middle East, the outburst of terrorism in recent weeks, which has included a series of assassinations of Arab diplomats in Europe representing various nations, stems from a series of factors, some of them interrelated: - The shifting alliances and deepening divisions in the region, which see Jordan and Egypt trying to form an axis of moderate Arab nations to oppose Syrian influence. - The split within the Palestine Liberation Organization, in which Yasir Arafat has aligned himself with King Hussein of Jordan to preserve his leadership from the challenge of Syrian-backed factions. - The rise throughout the area of Islamic fundamentalism, particularly among Shiite Moslems in Lebanon and elsewhere, influenced - and aided - by Ayatollah Ruhollah Khomeini's Iran.

THE policy question concerning human gene therapy is no longer whether to attempt such treatments, but when trials in patients should begin, according to a report released yesterday by the Congressional Office of Technology Assessment. Gene therapy designed to treat individual patients without causing changes that could be inherited is just an extension of conventional medical science and technology and does not raise new ethical issues, the report said. ''The factor that most distinguishes it from other medical technologies is its conspicuousness in the public eye,'' the report said. Some critics have asserted that such treatments would be the beginning of misguided attempts to redesign the human race.

Walter Gilbert, a Nobel Prize-winning biochemist, resigned yesterday as chairman and chief executive of Biogen N.V., one of the companies in the forefront of the search for an anticancer drug. Biogen has been reporting sizable losses, and analysts speculated that Mr. Gilbert may have been under pressure to resign. In an announcement from Cambridge, Mass., where it has laboratories, Biogen said that the 52-year-old Mr. Gilbert would remain a member of the company's board and its scientific oversight committee.

Now that years of sparring with the Securities and Exchange Commission over his business practices are behind him, Robert E. Brennan, founder and chairman of First Jersey Securities Inc., is remaking his image and that of his firm. Instead of being seen as the force behind an aggressive Wall Street broker, peddling low-priced ''emerging'' companies, the boyishly handsome Mr. Brennan would now like to be known as a committed corporate citizen, a generous philanthropist: in effect, turning a dark cloud into a halo. And he is going after that goal in the same determined spirit in which he pursues everything - handing out press clippings about his recent $5 million gift to his old high school and planning a catchy advertising campaign for television. The first step in this transformation was the consent decrees that First Jersey and its chief signed on Nov. 20, ending a five-year battle with the S.E.C. The commission dropped its charges of price manipulation, but in return First Jersey and Mr. Brennan were enjoined from breaking the securities law. If they do, they will face criminal charges, rather than the usual civil penalties. First Jersey is the only Wall Street firm working under such an injunction, according to the S.E.C.

The Manufacturers Hanover Trust Company cut its prime lending rate yesterday by half a percentage point, to 10 3/4 percent, the lowest level since August 1983, when it stood at 10 1/2 percent. Although no other major banks immediately followed the move, it was widely believed most would do so shortly, probably today. Some predicted that the prime rate would soon drop even lower.

TUESDAY, DECEMBER 18, 1984 International China's new ''responsibility system,'' which lets peasants who produce more earn more, has been a general success. Since the policy change was announced in late 1978, China's output of grain and potatoes has increased nearly 5 percent a year to reach a record 387 million tons last year. Now that the 800 million peasants are no longer forbidden to find ways to earn money on the side, their average income has more than doubled since 1978 to reach 310 yuan, equivalent to about $117, a person in 1983. However, some regions are still gripped by poverty. (Page A1, Columns 3-4.) Mikhail S. Gorbachev told Sir Geoffrey Howe, the British Foreign Secretary, that the Soviet leadership considers it ''especially important to avert the transfer of the arms race to outer space.'' Mr. Gorbachev, the Kremlin's second in commmand, said, ''If it is done, then it would be unreal to hope to stop the nuclear arms race.'' (A3:1-3.)

An article in Metropolitan Report on Friday about the manslaughter conviction of Joseph Brennan for a killing at a Manhattan video arcade gave his address incorrectly. He lives at 227 East 57th Street.

WITH bounding curiosity and a theory to establish, astronomers are searching the northern skies for a star they call Nemesis, a small, dim companion of the Sun. Nemesis may or may not exist, but the quest goes on and soon will expand to the southern skies. Other astronomers, similarly inspired, have revived interest in finding Planet X, the putative body that has long been sought beyond Neptune and Pluto. They are examining new data from a spacecraft for evidence of the planet's existence. Some of the best minds of science are thus at play these nights and days in a provocative and promising attempt to understand how the heavens may hold the answer to what happened to the dinosaurs and, more important, what caused all the mass extinctions that, according to new fossil evidence, seem to afflict the Earth every 26 million years or so. This effort may lead to a new view of mass extinctions and their possibly decisive role in evolution.

SOCIAL anxiety, in its many forms, is epidemic. About 40 percent of Americans think of themselves as shy, while only 20 percent say they have never suffered from shyness at some point in their lives. Nearly one in four men and one in eight women report high anxiety when going out on a date, while a third of men and almost a half of women report such feelings at dances and discoth eques. And the most frequent fear in one survey of 3,000 adults was found to be speaking before a group. ''Social anxiety can be the surface sign of much deeper psychological conflicts, such as hidden hostility or guilt,'' said Seymour Epstein, a clinical psychologist at the University of Massachusetts, who has written extensively on anxiety and personality. While there have long been people who complained of social anxiety, as well as those who have sought to cure the problem, of late there has been a mushrooming of serious research by social psychologists on the topic, and new clinical treatments offered for those who view ordinary social contacts as dangerous and threatening.

A little more than a year ago, a Buffalo jury gave Mario Liberta a dubious distinction. He became the first man in New York State to be convicted of raping his wife. For more than two centuries, husbands like Mr. Liberta, a 26-year-old Buffalo resident now in state prison here, were exempted from the rape laws of New York. He was convicted - the only man ever convicted - under a narrow exception that permits prosecutions when the couple live apart. In an appeal now before the Court of Appeals, the state's highest court, Mr. Liberta, charged with raping his wife in front of their 2-year-old son, has argued that the law singled him out unfairly. In addition, 36 women's groups have agreed with him, at least in part, and have asked the court to declare the law unconstitutional.

chen Qingfan, a husky middle-aged farmer, sat in his whitewashed adobe house with a pounded earthen floor and recalled the years of poverty before the water came. ''In this place, we had no rain for 9 out of 10 harvests,'' Mr. Chen said. ''We relied on the weather and we lived by the weather. If there was rain, we got a harvest. If there was no rain, we got nothing.'' Barely an inch of rain a year falls on Mr. Chen's parched land in the yellow hill country of Gansu Province in China's northwest. Until this year, the farmer, his wife and five children earned 50 yuan a year per person

-TROY HILLS, N.J. WHEN the school district here was preparing its application this fall to take part in New Jersey's ''master teacher'' program, it was careful not to offend the local teachers' union by suggesting that it wanted to identify one teacher as better than another or deserving of more pay for the same work. If the district is selected for the state program, 29 of its 580 teachers could get a $5,000 pay raise next year, but they would have to spend a month of summer vacation revising the district's curriculum and would be tapped for special jobs when school is in session. ''We'll use them to do the things you never have the extra bodies to do,'' said Ruth Krawitz, the district Superintendent. ''The words 'master teacher' are not even used'' in the plan the district sent to Trenton, she said. ''That is why it was so palatable to the union.''