 Read the following passage:

"Ninian bought one of those smallish, almost identical houses that mushroom on the fringes of a city after every war, particularly where intensive bombing has created a number of desirable building sites."

What, in that passage, is symbolic?
By EVELYN E. SMITH Illustrated by DILLON [Transcriber's Note: This etext was produced from Galaxy Science Fiction August 1957. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] No one, least of all Martin, could dispute that a man's life should be guarded by his kin—but by those who hadn't been born yet? Nobody in the neighborhood was surprised when Martin's mother disappeared and Ninian came to take care of him. Mothers had a way of disappearing around those parts and the kids were often better off without them. As for his father, Martin had never had one. He'd been a war baby, born of one of the tides of soldiers—enemies and allies, both—that had engulfed the country in successive waves and bought or taken the women. Sometimes he wondered who Ninian really was. Obviously that story about her coming from the future was just a gag. Besides, if she really was his great-great-grand-daughter, as she said, why would she tell him to call her " Aunt Ninian "? Maybe he was only eleven, but he'd been around and he knew just what the score was. It was safer with Ninian, though, because when he pushed her too far, she would cry instead of mopping up the floor with him. "But I can't understand," he would say, keeping his face straight. "He's dissatisfied with the current social order and killing you is part of an elaborate plan he's formulated to change it. What's it all about in straight gas?" "Oh, just don't ask any questions," Ninian said petulantly. So Martin held his peace, because, on the whole, he liked things the way they were. All the people he knew lived in scabrous tenement apartments like his, but she seemed to think it was disgusting. "So if you don't like it, clean it up," he suggested.
 "houses that mushroom on the fringes of a city after every war, particularly where intensive bombing has created a number of desirable building sites," is symbolic of the way things like the atom bomb, that leaves a mushroom cloud in its wake, are thought to have been unleashed upon the world to preserve or "create" things that will be "desirable" for society.
 "houses that mushroom on the fringes of a city after every war, particularly where intensive bombing has created a number of desirable building sites," is symbolic of the way things like the atom bomb, that leaves a mushroom cloud in its wake, are thought to have been unleashed upon the world to preserve or "create" things that will be "desirable" for society.  "intensive bombing" is symbolic of what the descendants imagine they are doing to Martin to make sure they impart enough of their future society on him to make him agreeable to carrying on with their way of life.  The word "bought" is symbolic of the wealth Martin is to bring to future worlds.  "Smallish, almost identical houses," is symbolic of the way that Ninian blends in with current society.