Fandom questions are on-topic ...
See Why is fandom information treated as if it weren't on topic? There's an occasional problem on this site with people voting to close fandom questions because they aren't familiar enough with the site scope to know that behind-the-scenes and fandom information is explicitly on-topic here. This much of Skooba's answer is correct, and most of the questions he lists have been well-received, being out-of-universe fandom questions relating to specific works of sci-fi or fantasy.
... but not every fact about an author is fandom information.
The question under consideration here isn't a question about the Harry Potter series/universe, nor about JK Rowling as a fantasy author. It's a question about JK Rowling as a person, and JK Rowling as a person isn't a science-fiction or fantasy entity.
I think a lot of the dispute here arises from the fact that JK Rowling is primarily known as an author of fantasy. Imagine if the question was about the personal lives of the models / TV personalities Kendall and Kylie Jenner (who once wrote a science fiction novel), or of the physicist Stephen Hawking (who's written a series of children's science fiction books). I doubt anyone would hesitate in closing "Who is Kylie Jenner going out with?" or "Has Stephen Hawking ever owned a dog?" as off-topic.
Questions such as Did Tolkien have experience with addiction? or Is Tolkien prejudiced against the East? are directly related to Tolkien's fantasy writing. They're not just asking for factoids about his personal life; they're asking whether Tolkien's portrayal of addiction and of Easterners in The Lord of the Rings was influenced by his real-life experiences or views. But with questions like What is JK Rowling "bad" at? and Was Tolkien a driver?, the connection is far more tenuous.
So the question we need to ask for such a question is:
Is it justifiably connected to an SF/F work?
Valorum's answer is essentially correct, although I'd phrase the key criterion as relevancy rather than notability, but he also says (having answered it) that the Rowling question is fine. I leave it up to you:
- If you think the question is relevant to Harry Potter, or any other SF/F work, leave it open.
- If you think its relevancy is too much of a stretch, vote to close it.
(I say "justifiably" because it's possible to draw a connection to almost any question about an author from their work, if you're willing to stretch its credibility enough. If a question tries to make a connection which you feel is too tenuous or ridiculous, you can still vote to close it.)