Thanks for the suggestions. I mostly remember that as an "aliens made them do it" story, though. I don't recall ever learning anything about the puffballs except that they were a wacky plot device for sex, though it has been a long time since I read it. I didn't exclude AMTDI again under point two because it's not that common for non-human alien stories, but since there's fans who maintain specific AMTDI thematic lists already, I don't list that genre, unless there's more to the aliens. Do I remember the story wrong and the aliens are more than a sex-pollen device? Then I'll list it.