Most of the above contributors have made valid points, and #9 pointed out that fantasy and science fiction utilize many of the same "plot types, character archetypes, and fantastical settings." Got it in one: they fall under the umbrella of "speculative fiction," as do dystopias, utopias, "doomsday" literature, alternate histories, much occult literature, paranormal romance, much horror fiction, "space opera," and much of myth and folklore. Speculative fiction may be loosely defined as the fiction of "what if?" What if the genders WERE equal? What if humans had metapsychic powers? What if FTL travel were discovered? What if NON-humanoid sentient races visited earth? What if plants were sentient? What if magic were real? What if females could be heroes instead of heroines? [Honest confession being good for the soul, I hereby confess that this "what if" has been a major focus of my reading, research, teaching, lecturing, and publishing.]
Yes, the post-WWII boom in science fiction DID appeal to a male audience and involve primarily male writers: we had a HUGE population of mostly male G.I.s whose view of the world was forever changed by the atrocities of WWII. A similar surge in speculative fiction occurred after Viet Nam, with a similar audience of traumatized veterans and their often-puzzled families and friends. But women were active in and before both surges, often under male pseudonyms; being constrained by gender is certainly NOT exclusive to female authors of speculative fiction, nor is it a recent situation. Such luminaries of speculative fiction as Alice Sheldon [James Tiptree], C.J.Cherryh, C.L. Moore, Megan Lindholm [Robin Hobbs], Jacqueline Lichtenberg [Daniel R. Kerns], Andre Norton [enotes has a superb article about her], Mickey Zucker Reichert, Anne Rice [A.N. Roquelaure], Chelsea Quinn Yarbro [Quinn Faucett], Jo Clayton, Julian May [Ian Thorne], Leigh Brackett [George Sanders], and even J.K. Rowling have written/published under either male or gender-neutral pseudonyms.
Julian May's magnificent "Saga of Pliocene Exile/Galactic Milieu" series, comprising a quartet, a trilogy, and a duology, proves definitively that women CAN handle "equipment" novels, and handle them with a rare flair for universe-building. Elizabeth Moon, Sherri S. Tepper, C.J. Cherryh, Melissa Scott, Jo Clayton, Leigh Brackett [she wrote the first draft of "The Empire Strikes Back"], Lois McMaster Bujold, Anne McCaffrey, Mercedes Lackey, Barbara Hambly, Sharon Shinn, Nancy Kress, Niccola Griffith, Vonda McIntyre, Patricia Kennealy-Morison, A.C. Crispin, and a host of others demonstrate that they can incorporate real technology into, and/or handle "equipment" gracefully, and/or interweave "hard" science with, their speculative fiction, seamlessly. Numerous women have written for such technology-intensive series as "Star Trek" and its descendents, "Star Wars" and its descendants, and "Quantum Leap."
I’ve said all that to say this: science fiction is MUCH less dominated by men than in the past -- and the genre has benefited greatly from its increased leavening by women writers.