What was going on when I was born?

A dispatch on the Washington Talk page yesterday about furniture rentals carried an incorrect byline. The writer was Amy Wallace, not William N. Wallace.

AUTISM, a severe mental disorder that becomes evident in infancy, seems to have a genetic cause, according to a study of twins reported in the current issue of The American Journal of Psychiatry. The study was a rigorous one that sought out identical (one-egg) twins and fraternal (two-egg) twins in which at least one partner was suspected of having the disorder. In this way, the genetic contribution could be readily identified.

''Today, the 22d of January 1985, I am well and my friends Benjamin Weir and Jeremy Levin are also well.

Time Inc. and Newsweek have only lately discovered what some specialty publications have known for years: the value of the single-advertiser issue. Both publications have been experimenting with the one-sponsor, one-issue format, a staple of such magazines as Moviegoer and Veterinary Practice Management, which are published by the 1330 Corporation in Knoxville, Tenn. And both say they expect to go on using the device. ''Success tends to breed success,'' said Ken Noble, a Paine Webber Inc. analyst.

One of five Americans apparently kidnapped in Beirut over the last 10 months was seen today in a 56-second videotape in which he called on the United States to ''take action for our release quickly.'' However, the American, William Buckley, a political officer in the United States Embassy in Beirut, did not specify what Washington had to do to gain freedom for the five. On the videotape, Mr. Buckley said that he and two other missing Americans were well. He mentioned Jeremy Levin, the Beirut bureau chief for the Cable News Network, and the Rev. Benjamin M. Weir, a Presbyterian minister.

The Reagan Administration now predicts significantly lower inflation this year than it had been expecting as recently as a month ago, according to economists who have helped prepare the forecast that will be part of the President's new budget proposal. The Administration has made no change in its year-old forecast of relatively strong 4 percent economic growth for this year and thus no change in its expectation that the overall unemployment rate will drop only slightly, from 7.1 percent in December to 6.9 percent at the end of 1985. But the budget documents will show inflation of 4.3 percent this year, well below the 4.7 percent estimate that the Administration used in preparing the budget in December. Broader Statistical Basis The inflation figure is based on the price deflator of the gross national product, which is more comprehensive than the better known Consumer Price Index because it reflects changes in buying patterns.

TOM BECK, homing in on the radio-beacon collar of a sleeping black bear, digs through 10 feet of snow to reach the entrance to its den. He takes blood samples and rapidly retreats, as part of a revealing new study of the chemistry of hibernation. If the dangerous bear wakes, Mr. Beck crawls back out of the cave as fast as he can. ''I never wear a gun on my belt,'' he said. ''There would be no time to use one.'' But he adds that the bears normally don't follow because ''they only want to get you out.''

The nation's farmers face at least six more years of economic hardship if current Government policies are continued, according to a study by a Congressionally financed policy research institute. Changes in farm policy proposed by the Reagan Administration would make matters worse, according to projections in the study, conducted by the Food and Agricultural Policy Research Institute of the University of Missouri and Iowa State University. Furthermore, the study's projections indicate, even robust improvements in nonfarm economies around the world would do little to help troubled American farmers. Concern Over Farm Economy The study comes against a background of growing concern over American farmers' economic troubles. One recent survey, for instance, reported that 28 percent of Iowa's farmers had debts heavy enough to make it questionable whether they could survive.

GEORGE W. WINGATE High School in the Crown Heights section of Brooklyn, like so many other high schools in New York and elsewhere, faces the problem of trying to educate students who enter high school with reading scores still at the elementary school level. But a study of ninth graders who started at Wingate last fall indicates that some low scores may be misleading. The study shows that, when the time limits for tests are eased, the students are capable of reading and understanding work on a higher level than would be presumed from their scores on timed, standardized tests. ''The bottom line is that the study demonstrates that inner-city youngsters, and, by implication, other minorities in the country, can read signficantly better than the standard reading test scores show,'' said Robert L. Schain, the principal of Wingate.

International Iraq said it had carried out its first ground attack against Iran in nearly three years. It said the drive involved 40,000 troops backed by air cover and artillery. Iraq said its forces had advanced to new positions while Iran said ''not an inch'' of territory had been lost. (Page A1, Columns 3-4.) An American captive in Lebanon was seen in a 56-second videotape in which he called on Washington to act quickly to gain the release of five Americans apparently kidnapped in Beirut over the last 10 months. But the American, William Buckley, who was a political officer in the United States Embassy, did not specify what Washington had to do to free the five captives. (A1:2-4.)

The chairman of the Metropolitan Transportation Authority warned today that New York City bus and subway riders could face a fare increase of up to 25 cents next year if Federal aid was slashed and the state failed to increase its support. The M.T.A. chairman, Robert R. Kiley, said suburban commuters who relied on the Long Island Rail Road and the Metro-North Commuter Railroad could experience fare increases of as much as 10 percent. ''This is the most serious threat to mass transit by any Administration, by far,'' said Mr. Kiley, who was in Albany to meet with legislative leaders and aides to Governor Cuomo. The Reagan Administration, Mr. Kiley said, is proposing a cut of 75 percent in capital assistance to mass transit - money used for major construction and the purchase of new trains and buses - and a total elimination of operating aid.

Because of an editing error, an obituary yesterday of Joseph J. Sanchez, a General Motors executive, gave the date of his death incorrectly. It was Saturday.