more than their brothers because of the curse and the disgrace Oedipus brought to his family.

OEDIPUS. ...Though I cannot behold you, I must weep
In thinking of the evil days to come,
The slights and wrongs that men will put upon you.
...Who then will wed you? None, I ween, but ye
Must pine, poor maids, in single barrenness.
...To you, my children I had much to say,
Were ye but ripe to hear. Let this suffice:
Pray ye may find some home and live content,
And may your lot prove happier than your sire's.

When Sophocles wrote Oedipus Rex, he knew quite well what was going to happen to Antigone and Ismene, because he'd already written a play about them. Sophocles wrote Antigone in about 441 BCE, twelve years before he wrote Oedipus Rex. Sophocles also wrote Oedipus at Colonus, the third of the "Theban Plays," shortly before his death in 406 BCE, and it was performed at the Festival of Dionysus in 401 BCE.

Sophocles wrote the plays out of order. Chronologically, the events in Oedipus Rex actually occur first, followed by the events of Oedipus at Colonus and then by the events in Antigone.

After the events of Oedipus Rex, Oedipus and his four children live in Thebes until the children are young adults. Oedipus then exiles himself to Colonus, and he takes Antigone with him to care for him as he grows old. Ismene, Eteocles, and Polynices stay behind in Thebes. Creon steps down as king, and Eteocles and Polyneices agree to share the throne of Thebes.

As Oedipus at Colonus begins, the arrangement between the brothers has lasted for about a year, until Eteocles decides that he doesn't want to share the kingdom anymore and that he won't give up the throne when it's Polyneices turn to be king. This causes a civil war between the brothers.

Ismene travels to Colonus to tell Oedipus and Antigone about the problems in Thebes that have led to a civil war. Oedipus curses both brothers, and Oedipus refuses to talk with Polyneices, who has travelled to Colonus to ask for Oedipus's support in his war against Eteocles.

Oedipus relents and agrees to talk with Polyneices but becomes enraged at him. He tells Polyneices that he deserves his fate and prophecies that Polyneices and Eteocles will kill each other in the civil war. Polyneices returns to Thebes.

Oedipus dies and is buried in Colonus, and Antigone returns to Thebes.

As Antigone begins, the civil war in Thebes has ended, and, as Oedipus prophesied, Eteocles and Polyneices kill each other in the war. Creon is king of Thebes again, after the deaths of Eteocles and Polyneices, and he decrees that Eteocles will be accorded a hero's burial because he fought on the side of Thebes. He also decrees that Polyneices must be given no burial, under pain of death, and that his body must be left in the desert.

Antigone disobeys Creon's decree, and Creon condemns her to death. Ismene disappears from the play after Antigone is sentenced to death, and no further mention is made of her.

Creon has a change of heart—after being threatened with various horrors by the gods—but Antigone kills herself in the cave where she was buried alive before Creon can release her.

In summary, Oedipus's children Eteocles and Polyneices kill each other, Antigone dies in a cave, and Ismene apparently survives.

There is a further myth attached to Ismene, in which Ismene is betrothed from childhood to Atys, the son of Croesus, king of Lydia. Atys fought and died in the civil war in Thebes in which Eteocles and Polyneices killed each other.

Tydeus, the man who killed Atys in the war, later killed Ismene at the instigation of the goddess Athena, who was jealous of Ismene and upset with her for making love with Theoclymenus, a prophet from Argos.

In all, Oedipus's children all suffered fates worse than his own, as Oedipus feared and predicted and as the gods decreed.

Oedipus and Jocasta have four children, two boys (Eteocles and Polyneices) and two girls (Antigone and Ismene). At the conclusion of that play, all four children are very much alive.

At the conclusion of the play, Oedipus indicates that the two boys are grown up and are able to take care of themselves.

 As for my two sons, Creon, there’s no need
 for you to care for them on my behalf—
 they are men—thus, no matter where they are,
 they’ll always have enough to live on.
(Ian Johnston translation)

As anyone who has read Sophocles' Antigone knows, however, Polyneices and Eteocles eventually wage war against one another for the kingship of Thebes and end up killing each other in battle.

As for Oedipus' daughters, Oedipus predicts that life for them will be difficult, that they will be outcasts in Theban society, and that no one will want to marry them due to their father's shame:

When you’re mature enough for marriage,
who will be there for you, my children,
what husband ready to assume the shame
tainting my children and their children, too?
(Ian Johnston translation)

Again, readers of the Antigone will recall that Oedipus prediction is only partially true. Antigone herself does become engaged to marry Creon's son Haemon, but eventually she kills herself before that takes place. Haemon also kills himself not long after Antigone's death.