Is God a man or a woman?
Definitive answer: God is sexless.
The differentiation of organisms into sexes evolved because it increases fitness. Specifically, sex allows species to spread useful mutations throughout the population quickly, thereby avoiding extinction. It’s not useful enough in every species to justify the cost; species with large populations benefit more from sex.
Sex ratios vary. One boy can inseminate lots of girls so 1:1 only happens under special circumstances. Some organisms have more than two sexes. Or just one.
What we call "females" are organisms that make regular-sized gametes (eggs)—OK, maybe they got a little bigger in response to the development of "males"—those who evolved to make lots of small gametes (e.g. human sperm). In species with many sexes, each “mating type” cannot reproduce like with like.
Reproduction v Recombination v Sex
Reproduction (birth) and recombination (meiosis) do both occur in isogamous species, like paramecium. Some isogamous species produce gametes and some do not. Think bacteria v trees v mites v fungi v disgusting parasites. All part of creation.
I assume God is not acted on by natural selection—that is, that God does not reproduce, mutate, and have selective mutant offspring killed off.
The usual concept is that God is immortal and unchanging. God doesn’t produce gametes (right, Leda?)—just telekinetically impregnates virgins, whose offspring usually lecture about enlightenment and goodness before passing away childless (right, Linda Fiorentino?).
Sex is generally much more complicated in nature than it is in humans. Sex evolves because of selective pressures. God does not experience selective pressure or bear new godlings that experience selective pressure. So there would be no reason for God to evolve a sex. So God is sexless.