What was going on when I was born?

FROM the Ringling Brothers to the Felds, father and son, from the Fratellini clowns to the Flying Wallendas, the circus has always been a family business. Children are ''born into the circus.'' Generations of aerialists, gymnasts and lion tamers are swept into dynasties. The current edition of the Ringling Brothers and Barnum & Bailey Circus in residence at Madison Square Garden is, in at least this one respect, archetypal. It is a family of families: the Kovatchevis, Dukovis, Parvanovis, Bauers, Brauns, Antaleks and, of course, the Gebels. For many seasons, the hallmark of the Greatest Show on Earth has been Gunther Gebel-Williams, the death-defying animal trainer. This time he is accompanied by a gaggle of Gebels: his wife, daughter and 12-year-son, Mark Oliver Gebel.

With sales of its small cars languishing, the General Motors Corporation announced today that it was cutting its auto loan rate to 9.9 percent from 11.9 percent for consumers who purchase its compact and subcompact cars and light trucks. The Ford Motor Company quickly responded with a comparable program. The Chrysler Corporation, G.M.'s other major domestic competitor, is expected to follow G.M.'s lead in the next few days. The G.M. and Ford programs, covering loans of any term, are available beginning Friday on 1983 models delivered by May 31, when the program ends, or ordered by April 30.

A tentative contract agreement was reached today between N.J. Transit and a faction of the United Transportation Union that struck nine state-owned rail lines March 1. Another faction of the union that has honored the monthlong strike and refused to work walked out of negotiations moments before the settlement was announced. Despite the division, John P. Sheridan Jr., Transportation Commissioner of New Jersey, expressed hope that the striking faction would ratify the agreement at a meeting scheduled for Saturday morning and that trains for 70,000 commuters would be operating again by Monday morning. ''We think, in analyzing the whole situation, that our choice was to forge ahead and get the trains moving again,'' Mr. Sheridan said. ''We have no indication there will be a strike by the other union group. We will work all weekend, and we hope to have trains running by Monday.''

The problems in fabricating the metal space frame that will form the centerpiece of New York City's new Convention Center have been partly resolved, the president of the Convention Center Development Corporation said yesterday. The official, George Schoepfer, would not estimate the extra costs or the construction delays that the problems would cause. But he acknowledged that to complete the building, the corporation would need to make use of $24 million in interest expected from the $375 million in bonds it issued, bringing the final cost to at least $399 million. The corporation pays interest to its bondholders but also earns interest on the money it holds before it is spent.

News Analysis Last Christmas, President Reagan was feeling beleaguered by Democrats who were riding high after their November election victories. His programs were under wide attack, and he told aides he felt there was ''nobody out front'' making his case. ''I want to get out there and tell my side of the story,'' he declared. His speech on arms control in Beverly Hills today culminated an extraordinary personal effort over the last three weeks that stemmed from that frustration last December. Using the pulpit of the Presidency, Mr. Reagan has taken the political offensive and demonstrated his capacity to dominate the political arena on such issues as military spending and arms control, where his policies have been under fire. He has pushed the controversy over the Environmental Protection Agency out of the limelight.

International An earthquake death toll of 200 was feared in the devastated mountain city of Popayan, Colombia. At least 60 bodies were found and 500 people were injured in the quake, which demolished many buildings, including a Roman Catholic cathedral where 50 to 100 people were worshiping. The Mayor said at least 3,000 houses were in ruins. (Page A1, Columns 1-2.) Israel will not get 75 F-16 fighters until it withdrawns its forces from Lebanon, President Reagan said. He implied that Israel had violated the terms of an arms supply agreement with Washington stating that American military equipment may be used only for defensive purposes. (A1:5.)

Joseph V. Ossorio, chairman of the Drysdale Securities Corporation, pleaded guilty yesterday to Federal charges that he had made fraudulent reports inflating the value of investment accounts involving several million dollars. According to United States Attorney John S. Martin Jr., the charges stem from ''a major ongoing investigation'' into Drysdale's trading practices. They led in May 1982 to the collapse of the company and to approximately $300 million in losses for the Chase Manhattan Bank and other traders in Government securities.

''I think I like it even better than Easter morning services.

THERE is much for families to do without leaving the city this Easter weekend, and a lot of it has to do with eggs. You can roll, toss and avoid eggs at the Bronx Zoo, push eggs across Central Park, hunt for eggs in Van Cortlandt Park Stadium or at the Sheraton Centre and see eggs turn colors on Second Avenue. Non@-egg activities include racing, dancing, yelping and, of course, the Easter Parade, which is no parade at all - just a communal midtown amble on Fifth Avenue that gets under way in force at about 11 A.M. on Sunday. The most ambitious activity is the Bronx Zoo's third Great Egg Event tomorrow and Sunday from 11 A.M. to 3 P.M. It celebrates not only eggs but also what emerges from them. All kinds of newborns are waiting to be seen, including some that aren't hatched. Just arrived are 12 mouflon lambs, four nyala antelope, a white-tailed gnu, pink pigeons, a proboscis monkey, snakes, crocodiles and tortoises.

President Reagan said today that until Israel withdraws its forces from Lebanon, he will not permit the transfer of some 75 F-16 fighter jets that have been held up since last summer. ''We are forbidden by law to release those planes,'' Mr. Reagan said. He implied, but did not state explicitly, that Israel had violated the terms of an arms supply agreement with the United States stating that American military equipment can be used only for defensive purposes. Under the Arms Export Act, the President has discretionary authority to cut off military sales to any nation found in substantial violation of such an agreement.

The Justice Department is checking possible antitrust violations by four American oil companies that pump oil in Saudi Arabia. Page D3. Nigeria said yesterday that it would keep its oil prices unchanged, despite the price cuts proposed the day before by the British National Oil Corporation, Nigeria's principal competitor outside OPEC. The Nigerian decision not to lower its prices thus eliminated one of the key threats to the pricing structure adopted by the Organization of Petroleum Exporting Countries in early March.

Much of the southwestern mountain city of Popayan was devastated today by an earthquake that killed at least 60 people and injured 500. But with the Roman Catholic cathedral and other buildings in ruins, it was estimated that the death toll would reach at least 200. The earthquake struck at 8:15 A.M., sending roofs of houses flying through the air, toppling buildings and shrouding the city of 135,000 people with a cloud of dust. It was estimated that 50 to 100 people were worshiping in the Spanish colonial-style cathedral when it collapsed. The police reported during the day that 25 bodies had been recovered from the rubble, but that the search there had not yet been completed. They said 35 bodies had been recovered from houses and some hotels.