Is Demeter a girl or boy?

Two things come to mind, that as a goddess of growing - Demeter when wronged, was also goddess of crop failure; hunger and starvation. Demeter was also a main goddess in a mystery cult that promised passage to Elysium in the Underworld, her brother and son-in-law Hades was king of the underworld, and her daughter Persephone the queen. So making her mad could result in death, and a very bad "afterlife". What is called "the Great Famine" happened when Persephone was taken and Demeter searched for her daughter, her cold (wintery) fury causing all plants to stop growing.

Individuals that felt her wrath include Askalabos, whom turned into a starry-spotted newt after calling the goddess greedy when seeing her drink something with barley. Askalaphos the son of Akheron and Gorgyra, bore witness against Persephone saying that she had ate when in the Underworld; in punishment for which Demeter pinned him down with a heavy rock in Hades' realm; later when Heracles freed him of this Demeter turned him into a horned owl.

Aithon / Triopeius / Erysikhthon, who cut down a holy poplar in Demeter's grove for his feasting hall: Demeter then made him burn with a hunger that could not be quenched, the more he ate the more he desired. Last of all, toward the end of his life, when a snake was sent to plague him, he suffered many ills, and at last winning death, was put among the stars by the will of Demeter. And so the snake, coiling round him, still seems to inflict deserved and everlasting punishment.

The above constellation Ophiuchus is also mentioned below.

Karnabon king of the Getae, was visited by Triptolemus sent by Demeter in dragon drawn cart to show men how to use grain and live more civilized lives: at first welcomed, Karnabon plotted treachery, slaying the dragon so Triptolemus could not flee from when he realized he was about to be put to death in a ambush. Demeter replaced the dragon, then killing him put him in the stars with a dragon in his arms as if about to kill it to remind all in warning. (Constellation Ophiuchus).

Kolontas when Demeter came to Argolis, while Atheras and MysiOS afforded hospitality to the goddess, Kolontas neither received her into his home nor paid her any other mark of respect - his daughter Khthonia did not approve: Kolontas was punished by being burnt up along with his house, while Khthonia was brought to Hermione by Demeter, and made the sanctuary for the Hermionians.

Lynkos received Triptolemus in Scythia where he ruled: when Triptolemus was asked how he had come, his journey's cause, his name and country.He answered: 'Famous Athenae is my country and my name is Triptolemus. No sail brought me by sea, nor foot by land, the sky lay wide to give me way. I bring the gifts of Demeter. If you sow them wide over your ploughland, they will give you back bountiful harvests, gentle nourishment.' Lynkos grew jealous of this and pretended hospitality, when Triptolemus slept Lynkos would have plunged a dagger into his heart and claimed the goddesses gift as his own to give to others: Demeter transformed the king into a lynx; then told Triptolemus to go homeward through the air which he did.

Minthe was a lover of Hades before Persephone, and when Hades brought Persephone back to the Underworld - Minthe complained and was jealous saying that 'she was nobler of form and more Excellent in beauty than dark-eyed Persephone and she boasted that Aidoneus would return to her and banish the other from his halls' so Demeter trampled her beneath her foot and destroyed her: from the earth mint (which bears her name) grows.

Pyrrhos (king of Epirus and Macedon: 319/318 BC-272 BC) was wounded in the head in an attack on the city of Argos. It is said that his death was caused by a blow from a tile thrown by a woman. The Argives however declare that it was not a woman who killed him but Demeter in the likeness of a woman. There is a sanctuary of Demeter, built at the command of the oracle, on the spot where Pyrrhos died, and in it Pyrrhos is buried.

Seirens: nymphs whom were transformed into bird-shaped monsters by Demeter. Some say this metamorphosis was a curse, a punishment for refusing to help in the search for Persephone, others a blessing, helping them in the search for their beloved mistress.

So while Demeter did do "bad things" they were justified in myths.