Is there a Halacha that sons may not be present at their parents' burial? I've heard that if the sons wasted seed (G-d forbid) negative forces are created which would be detrimental at the burial site so the Rabbis said that sons should never come for the actual burial. Anyone hear of something like this? (sources please)
The Chevra Kadisha in Yerushalayim strictly does not allow a person's children or grandchildren to be present at his burial. This is based on non-halachic, Kabbalistic considerations. This is not because of anything the son may have done, but because the person who passed away may be guilty of certain sins. In any case, I have never heard of this minhag being followed anywhere outside of Yerushalayim. Even in Yerushalayim, in the last few years they have become less vehement about this minhag, due to strong protests of families that were shocked to hear that they couldn't go with their parent or grandparent. But one cannot rely on this; if it is an important consideration, one would be well advised to purchase their plots outside of Har Hamenuchos or Har Hazeisim. The source, I've been told by members of the Chevra Kadisha, is a Zohar in Breishis, involving Adam and Chava and Kayin. I never saw it inside. It may be there, it may not.
I realize the answer would be more useful if I could cite chapter and verse. I can't, and I see no need to go digging, since it's not something that pertains for the communities outside of Yerushalayim, and, again, it is another example of Kabbala in opposition of mesora. Take it or leave it.
I found this: http://books.google.com/books?id=f83YJDHRZycC&pg=PA70
May a son attend the burial of his father? I have been told there is a problem of shedim. Is this possible?
Rabbi Shamah's response: Although some discourage a son from attending his father's burial, this is a practice not mentioned in the Talmud or in a single classical Jewish source including Shulhan Aruch. Rabbi Solomon D. Sassoon a"h considered it contrary to the spirit of the Torah and countermanding the misvah of honoring one's father. An excerpt from the Encyclopedia Judaica under the entry Demonology (v. 5 p. 1530) may help place this matter into better perspective.
"The sexual element in the relationship of man and demons holds a prominent place in the demonology of the Zohar... remarkably similar to the beliefs current in Christian and medieval demonology... these demons... need the human semen in order to multiply. In the later Kaballah it is pointed out that the demons born to man out of such unions are considered his illegitimate sons. At death and burial they come to accompany the dead man, to lament him, and to claim their share of the inheritance; they may also injure the legitimate sons. Hence the custom... in a number of communities (dating from the 17th century) of not allowing the sons to accompany their father's corpse to the cemetery in order to prevent their being harmed by their illegitimate step-brothers."