A double-standard?

  "The arms to shoulders joined are accounted to the Twins"
        -Astronomica, Manilius, p. 119.

  "From the Twins come less laborious callings and a more agreeable way of life, provided by varied song and voices of harmonious tone, slender pipes, the melodies inborn in strings and the words fitted thereto: those so endowed find even work a pleasure. They would banish the arms of war, the trumpet’s call, and the gloom of old age: theirs is a life of ease and unfading youth spent in the arms of love. They also discover paths to the skies, complete a survey of the heavens with numbers and measurements, and outstrip the flight of the stars: nature yields to their genius, which it serves in all things. So many are the accomplishments of which the Twins are fruitful."

        -ibid, p. 235.

  "The story most closely associated with Gemini is the legend of Castor and Polydeuces (Pollux in Latin) from Greek mythology. Castor and Polydeuces were identical twins born to Leda, Queen of Sparta, by two different fathers. Castor was said to be the son of Leda’s husband, King Tyndareus and thus mortal. Polydeuces was said to be the immortal son of Zeus, from Zeus’s seduction of Leda while he was disguised as a swan. The same encounter also produced Helen of Troy. Tyndareus adopted Polydeuces. The twins were inseparable and became known as the Dioscuri (sons of Zeus).

More Twins

  "Meanwhile, in another country, the wife of the half-brother of Tyndareus also gave birth to twin boys, Idas and Lynceus, and in a somewhat parallel legend, Idas was supposed to be the son of Poseidon. They had the same close relationship with each other as their cousins. Bad blood was generated between the two sets of twins when the Dioscuri kidnapped and had sons with the women who were betrothed to their cousins.

  "Years passed and both sets of twins became famous for various physical and mental skills. They all ended up on Jason’s voyage to find the Golden Fleece. During the trip they became reconciled and decided to go on a cattle raid together. There are many stories explaining why they reopened their feud. One story says that Idas cheated the Dioscuri of their fair share of the stolen cattle and the Dioscuri stole them back. A fight broke out and Idas killed Castor with a spear. Polydeuces then killed Lynceus.

Born of the Egg

  "A different version says that Castor killed Lynceus and demolished the monument Idas had erected to him, causing Idas to kill Castor, and Polydeuces to kill Idas. There are other stories that say these same three were killed in battles, raids, etc. Polydeuces survives in all versions.

  "Zeus granted Polydeuces' wish not to outlive his brother, but since Polydeuces was an immortal, they were still separated (as a mortal who died, Castor was destined for Tartarus). Polydeuces refused immortality unless Castor could share it, so Zeus allowed them to split their time in the heavens and under the Earth. To honor their brotherly love, he put an image of twins in the sky."*

  *http://chandra.harvard.edu/photo/constellations/gemini.html