I am not subscribed to that subreddit. I don't think I have ever viewed this subreddit, though its possible a post was linked from one of the other subreddits I have followed. I also don't have any kids using laptops for internet browsing (they are too young, not using our computers yet).
What's the deal? I'd rather not receive multiple desktop notifications of the trending posts every day in r/exmormon. There also doesn't seem to be a way to disable desktop notifications about a specific subreddit; you have to just nuke desktop notifications altogether, which is really really dumb.