question:  Why does Roger speculate there are more females than males in the fourth dimension environment?
context: 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. 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. 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. 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. 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. Olga sat up straight, her pale blue eyes round with utter disbelief. Dana stood almost in the center of the room, carmine-tipped fingers clasped beneath the swell of her breasts. Somehow it brings things closer...." This was so with all of their foods, with their cigarettes, with everything in their prison—or their cage. Their captors were utterly without a human conception of smell, living, apparently, in a world without odor at all. We seem to be in a universe of different properties as well as different dimensions. "But I'll settle for the fourth—a fourth dimension in space, if that makes scientific sense, because we don't seem to have moved in time.
output:  The ones controlling the environment have a more challenging time bringing males through the fourth dimension.
options:  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."