ZERO POPULATION GROWTH, an outfit that worries a lot about imbalance between people and resources, blossomed forth the other day with what it obviously took to be a neat gimmick to project its favorite anxiety. It was a list of "onlies," or only children, who are "famous folks." Said ZPG: "We can't claim they excelled in their various fields of endeavor because they were onlies, but it's an impressive list."

We turned to it eagerly: Ansel Adams . . . Alvin Ailey . . . Clive Barnes . . . Buddha . . . Buddha? Frankly, we had never thought of Buddha as some couple's only child. At Rudi Gernreich, we began to feel that ZPG was stretching. Frank Gilroy we didn't even recogize. (Sorry, Frank.) Al Pacino . . . Alexander Pope . . . Harold Robbins . . . and, well, Joseph Stalin. Of course, you can say this for Stalin: Having one of him would be enough to inspire almost anybody to stop.

Roger Staubach offered reassurance. And once thus back in the spirit of things, it was easy for us to imagine Buggy Sainte-Marie, Queen Victoria and Nancy Walker as a fated trio, linked by much more than their common lack of siblings. But, to be truth-eyes misted over by local pride, we could not immediately see what he had in common with Joseph Stalin, baldi. it was a relief, though hardly a surprise, to close out the list with two titans, Jonathan Winters and Emile Zola.

Aside from the accident or purpose, whichever it was, of their birth, is there a thread, a common theme, one relevant to the debates of Washington, running through this list? Willy Brandt, Richard Daley, Indira Gandhi, Tom Hayden: Politics was, in one way or another, unkind to all of them, as it was, we might add, to Mary, Queen of Scots, and may well yet be to Arthur Burns, although we do not suppose that President Carter intends to visit the same dismaying fate upon him. ZPG, we are sure, wouldn't take it at all well.