Halloween: The Curse of Michael Myers (1995)

Mrs. Blankenship: A long, long time ago, it was a night of great power. When the days grew short, the spirits of the dead, returned to their homes to warm themselves by the fire's side. All across the land, huge bonfires were lit. Ohhh, there was a marvelous celebration. People danced, and they played games, and they dressed up in costumes, hoping to ward off the evil spirits. Especially the boogey man.

Trivia: The production of the film was notoriously troubled. There were numerous writers working on numerous drafts of the script before one was finally settled on. Filming was hectic with many scenes being omitted or re-written on-set. And after the first cut was complete, a poor test-screening lead to the film going through drastic reshoots that altered much of the story, including the addition of a brand new ending, which had to be written around the fact that co-star Donald Pleasance passed away shortly after the end of principal photography.

Question: I've seen this movie three times and there is still something that I don't understand. What exactly is Michael Myers curse supposed to be and why does this curse involve him killing his family and their friends?