Is a Muslim sinful if he retorts in kind to the cursing of his elder or younger sister?

It is not permissible for a Muslim to be one who slanders, curses, is obscene, or vulgar; rather, he must refine his tongue. If someone insults him, he should pardon, forgive, and respond with goodness, as Allah Almighty has commanded. If the offender is a relative, then he is even more deserving of pardon, forgiveness, and kindness. It is permissible for the wronged person to retaliate with a similar insult, such as saying "May Allah disfigure you" to someone who said it to him, or "O dog" to someone who said it to him. However, it is not permissible to retaliate with something forbidden, such as declaring someone an infidel or lying, nor to insult someone's father if he did not wrong him.