FTB, take a deep breath and unwrap a chocolate bar. Remember Sam Vaknin, the self-obsessed Narcissist who makes his living by telling his truth?
This is from his page on having children:-
As siblings or progeny grow older, the narcissist begins to see their potential to be edifying, reliable and satisfactory Sources of Narcissistic Supply. His attitude, then, is completely transformed. The former threats have now become promising potentials. He cultivates those whom he trusts to be the most rewarding. He encourages them to idolise him, to adore him, to be awed by him, to admire his deeds and capabilities, to learn to blindly trust and obey him, in short to surrender to his charisma and to become submerged in his follies-de-grandeur.
It is at this stage that the risk of child abuse - from emotional incest and up to and including outright incest - is heightened. The narcissist is auto-erotic. He is the preferred object of his own sexual attraction. His siblings and his children share his genetic material. Molesting or having intercourse with them is as close as the narcissist gets to having sex with himself.
Moreover, the narcissist perceives sex in terms of annexation. The partner is "assimilated" and becomes an extension of the narcissist, a fully controlled and manipulated object. Sex, to the narcissist, is the ultimate act of depersonalization and objectification of the other. He actually masturbates with other people's bodies.
Once he's gone, you should tell the children a child-sized edition of the truth, by the way. Vaknin himself says so.