In case anyone wants to get some non-fiction reading in before
Here's the mother/son chapter of Gothic Incest: Gender, Sexuality, and Transgression by Jenny DiPlacidi.
It's open-access on JSTOR, about 34 pages, and is a great intellectual framework for understanding the "whys and whats" of what's going on if you need some help figuring out why we're incesting past like...just introducing horror and transgression. There are real story-telling reasons why the motif exists, past just being startling and discomforting.
It's also not too difficult to read. You might need some googling, just to get some phrases or see what theories/stories she's referencing, but it's not any more difficult that you'd see from any analysis I post on my blog.
