As it is brought in Kabbalah, “For during all those  years that Adam kept away from his wife [Chava, to ‘know her’], unclean spirits came and conceived from him, and bore offspring, which are called ‘plagues of the offspring of Adam’ (Zohar I:169b, Vayishlach). The ‘unclean spirits’, known as sexual shedim/demons, are called Lilim yemach shemo, and have origin in the feminine shed Lilit, yemach shemo. These are “impregnated” (see Avot d’Rebbi Natan 37:3) from the spiritual energy of semen (spilled in vain) which was ‘not’ used in kedusha (and in this manner, impurify man) and give birth to the ‘plagues’ – another class of shedim – which flit about in the world ‘filling the atmosphere’ together with the other hordes, such as the mekatrigim/accusers (see Zohar 190a, Vayeshev; 196b, Balak; R’ Chayim Palachi, Kaf HaChayim 240). Moreover, this progeny of shedim is very “special”, being that they are hybrid creatures of demoniac-souls (i.e., human neshamot that have no guf/body to be connected to, plus the Lilim, yemach shemo), which steal and so ‘starve these poor souls of their great vital energy’ (see Bamidbar Rabbah 16:25) since each neshama that is brought down from its source above receive spiritual sustenance.
Now, by Divine law, these plagues are as much considered the person’s children – for he was responsible for their fathering – as are their own children of flesh and blood in the world! These demoniac-souls then hunt their ‘causers of suffering’ (not the Lilim yemach shemo, but their human parents that initiated all these sufferings for them), staying close to them and seeking to siphon their spiritual energy. When a man dies, these ‘rebellious children’ accompany his coffin to the cemetery, mourning hin as now they cannot cling to that space and claim it (R’ Chayim Palagi, Tochachat Chayim, Shemot, pp. 29-30.). And as it is written, “When a man goes to the side of the Left and walks in impurity, he draws to himself all kinds of impure spirits, and an unclean spirit clings to him and refuses to leave him since these spirits cling only to those that cling to them first” (Zohar 55a, Bereshit). This connection causes man great mental confusion and the machshavot zarot/strange thoughts in his life and vengeance from these plagues on the afterlife! (ibid. Tochachat Chayim) Human beings are forbidden to father these “children”, for they profane the world and man, and seek to dominate humanity. This is contrary to G-d’s Law, which affirms: “Be fruitful, and multiply… and have dominion over the birds of the air” (Bereshit 1:28), to wit, all celestial creatures, for only “man was created in His image” (ibid. 27). It is good that man remembers in the image of Who he was created, so he can be one who is happily walking the straight path, “For the upright shall dwell in the land, and the innocent shall remain in it” (Mishlei 2:21), amen.