 Why does Roger speculate there are more females than males in the fourth dimension environment?
If it only had a lease that could be broken— Roger Tennant, crossing the lawn, could see two of the three wings of the house, which radiated spoke-like from its heptagonal central portion. That on the right was sundeck solar-house living-machine modern, something like a montage of shoeboxes. Dana was lying under a tree near the door, stretched out on a sort of deck chair with her eyes closed. Above it her comely face was sullen beneath its sleek cocoon of auburn hair. Their captors had no idea of how a woven design should behave. He could sense the restless stirring of the woman within Dana, just as he could feel the stirring toward her within himself—desire that both of them loathed because it was implanted within them by their captors. Within the dome of the barrier, it looked more like a well-kept if bizarre little country estate. The brook was practically water, but the small stones over which it flowed were of no earthly mineral. They entered the house, which had no roof, continued to move beneath a sky that glowed with light which did not come from a sun or moon. The other two women were sitting in the heptagonal central hall. Eudalia, who had borne twin girls recently, was lying back, newly thin and dark of skin and hair, smoking a scentless cigarette. Eudalia had been a female foreman in a garment-cutting shop before being captured and brought through. He turned to Olga, broad, blonde and curiously vital, who sat perfectly still, regarding him over the pregnant swell of her dirndl-clad waist. Olga had been a waitress in a mining town hash-house near Scranton. Tennant wanted to put an encouraging hand on her shoulder, to say something that might cheer her up, for she was by far the youngest of the three female captives, barely nineteen. "But he doesn't have to—have them," objected Olga. In fact, Tennant thought, only her laughter was unpleasant, a shrill, uncontrolled burst of staccato sound that jarred him to his heels. "Let's get the meal ordered," said Dana and they were all silent, thinking of what they wanted to eat but would not enjoy when it came. It arrived before the meal, materializing against one of the seven walls of the roofless chamber. Tennant watched the girls as a sweet-voiced crooner began to ply an unfamiliar love lyric to a melody whose similarity to a thousand predecessors doomed it to instant success.
 The ones controlling the environment have a more challenging time bringing males through the fourth dimension.
 Roger believes that the ones controlling the environment are running a breeding program to raise children who will eventually grow up to be body snatchers.  The ones controlling the environment have a more challenging time bringing males through the fourth dimension.  The ones controlling the environment are overwhelmingly male, heterosexual, and desirous of sex with women.  Roger does not make any kind of guess as to why he is in the minority among the women of his "harem."