What was going on when I was born?

In an effort to break a deadlock on this year's tax legislation, Senate conferees tonight offered to drop their major special tax cuts - including President Reagan's proposal to expand individual retirement accounts - if the House conferees would accept all the Senate's $12 billion in spending cuts, including $8 billion in Medicare. The Senate tax cuts total about $6.1 billion. The chairman of the House Ways and Means Committee, Representative Dan Rostenkowski, Democrat of Illinois, said immediately that the offer ''is the first indication that this conference can come to a successful conclusion.'' While Mr. Rostenkowski said he would reply when the conferees meet again Wednesday morning, he said, ''I think we are ready to do as much as we possible can,'' adding that the House response would be ''quite palatable.''

A 34-year-old Bronx man was charged last night with the slaying of 10 people in a house in the East New York section of Brooklyn last April, the police said. Police Commissioner Benjamin Ward identified the suspect as Christopher Thomas, of 899 East 169th Street. He said Mr. Thomas acted out of the mistaken belief that his estranged wife was having an affair with Enrique Bermudez, the owner of the house where the bodies were found. ''The suspect was placed at the scene of the crime and physical evidence was traced to Thomas,'' Commissioner Ward said at a crowded 10:45 P.M. news conference in the 75th Precinct station house in Brooklyn.

Allen Finkelson was no slouch in the law world. He graduated from Columbia Law School in 1971, and made partner at Cravath, Swaine & Moore - perhaps the most prestigious firm in the nation - a mere six years later. But it was not enough for him: ''I was very happy at Cravath,'' he said. ''I loved the people, but the prospect of doing what I was doing for 20 or 30 more years, without much change . . .'' he trailed off. ''Well, it was disquieting.'' So last October, Mr. Finkelson threw away the security of his hard- earned partnership - and partnership profits of hundreds of thousands of dollars a year - to become an investment banker at Lehman Brothers, now Shearson Lehman/American Express Inc.

Five years after it was bought by Avon Products Inc., Tiffany & Company is up for sale again. ''If a different owner can do more with Tiffany, and is willing to pay a fair price, then divestiture would be in the best interests of Tiffany & Company and of Avon shareholders,'' Hicks B. Waldron, who was appointed president and chief executive of Avon last September, said in a statement yesterday. Avon said more than 25 companies and individuals had expressed interest in acquiring the 146-year-old jewelry concern. Among the potential buyers are members of Tiffany's management, including William Chaney, who became Tiffany's chairman in January.

State legislative leaders announced final agreement today on a measure to require drivers and their front-seat passengers to wear seat belts in New York State. They said they planned to pass the measure Thursday; Governor Cuomo, who has called the bill ''a good idea,'' is expected to sign it. The Illinois Legislature is expected to approve similiar legislation in two weeks. The two states would be the first in the nation to require the use of seat belts.

The Democratic platform drafters favoring Walter F. Mondale became more conciliatory today and put into the statement of party principles a good deal of language that had been drafted by his rivals for the Presidential nomination, Senator Gary Hart and the Rev. Jesse Jackson. Only when the proposals of the opposition candidates ran specifically counter to Mr. Mondale's, which was two or three times in a long day, did the Mondale supporters take control and vote down proposed Hart and Jackson amendments. Relatively Mild Exchanges The session was generally amicable, with even less display of temper among the Democratic factions than the relatively mild exchanges at the opening meeting Monday. But Mr. Jackson, at a news conference in Philadelphia, characterized Mr. Mondale's interviewing of potential running mates a ''P.R. parade of personalities'' that did not broaden the Democratic Party. (Page A22.)

More than a decade after shifting to coeducation, many former women's colleges in the New York area say they are not attracting enough qualified male students. For years the schools have been strengthening science courses and establishing men's varsity sports programs in an effort to attract enough men so that at least 40 percent of their enrollment would be male. But at Sarah Lawrence, for example, only 17 percent of those who just graduated were men. At Manhattanville, the figure was 30 percent. At Skidmore, it was 35 percent.

New home construction dropped 10.5 percent last month, the Commerce Department reported today. The decline, to a still-strong seasonally adjusted annual rate of 1.78 million units, had been expected in light of rising interest rates. It followed a 19.7 percent gain in April.

The Senate, moving toward approval of its $230 billion military authorization bill, rejected an attempt today to impose a moratorium on deployment of nuclear- armed cruise missiles at sea. Still ahead, as the Senate moved through dozens of amendments, was a measure from Senator Sam Nunn, Democrat of Georgia, that would prod more military contributions from the Western European members of the North Atlantic Treaty organization. Senator Nunn said Administration officials, including President Reagan, as well as foreign officials had kept in touch with him on his amendment. On Monday, Senator Nunn said in a speech that the Atlantic alliance was not prepared to stop a conventional attack by the Soviet-led Warsaw Pact forces with conventional weapons.

SAN FRANCISCO AMERICA is flexing its gastronomic muscles, and nowhere is this more obvious than in California. Here, where chefs are as glamorous as movie stars and today's new dish is tomorrow's discard, preoccupation with the latest food trends surpasses most other leisure- time activity. But innovation, which has led to much-admired and often-copied creations, is, unfortunately, often practiced for its own sake. Freshness is the cornerstone of the cooking style that has been dubbed California Cuisine, which, despite its faddist tendencies, is remarkably straightforward. But, as was clear from a recent two-week visit to this state, there are a number of other characteristics, among them the following: * Grilling, especially with mesquite. * Combining cuisines that scarcely had a nodding acquaintance before, such as Japanese and French.

Companies John S. Reed will succeed Walter B. Wriston at Citicorp, sources within the bank said. Mr. Reed's appointment as chairman and chief executive, ending years of speculation, is to be formally announced today. Mr. Reed, who is 45, comes from the banking organization's consumer marketing operation and has almost no experience in lending to big business and governments. (Page A1.) Avon is seeking a buyer for Tiffany, which it bought only five years ago. Avon said the jeweler does not fit in with the cosmetic company's strategic plans. Among the more than 25 interested buyers are members of Tiffany's management. Avon hopes the sale will bring more than $160 million. (A1.)

The motion picture industry, whose rating system has been under attack recently by parents, movie critics and theater owners, is negotiating the first major change in its rating code since the system was introduced 16 years ago. The heads of several major studios said they had already approved a new rating of PG-13, which would put certain movies off limits to children under the age of 13 unless the children were accompanied by their parents or adult guardian. The new rating would fit between the current ratings of PG and R. The PG rating alerts the public to the need for parental guidance, but allows unaccompanied children of any age into the theater; an R rating requires children under 17 to be accompanied by an adult. ''The polling is going on now, but it isn't all in yet,'' said Frank Yablans, vice chairman of MGM/UA. Mr. Yablans said the idea of adding a new rating had been ''hotly debated'' for several years. He said that the polling began two weeks ago and that he expected the new rating to be approved by the end of July.