Dark thoughts or light? Worms or sky?
Sometimes dark thoughts are interesting, in spooky dramas or Stephen King novels. I've "raised" and kept and released worms. But if one's waking moments, meals, thoughts, bedtime stories and dreams are dark and negative, their children will be better off in school. It's one thing to go to goth night at the dance club. It's another thing to practice negativity and live (sort of live) in disdain of bright joy or humor.