I met him for the first time when I was 19, the same age my mother was when she met him. They had had unprotected sex a handful of times, before she got pregnant and he made a quick exit. I sought him out because I was lonely and angry at her. She'd stayed in an abusive relationship with a new partner for almost a decade, and when it ended, my self-esteem was wrecked and my confidence shattered. I wanted to find a parent who would love me unconditionally, who would protect me. The irony of what happened does not escape me.
If having sex with another adult is "failing to protect them," then someone is doing something wrong.
There were a lot of red flags over the course of those two years, moments I'm only now able to recognize as such.
I kept an eye out for those red flags.
So when my dad started talking to me openly about his past sexual encounters, it felt fairly normal.
Adults in personal relationships often talk with each other about sexual encounters, don't they?
On my second trip to Jamaica, I started sleeping in my dad's bed.
They weren't having sex at this point, but there's nothing wrong with sleeping together.
When I started feeling sexually attracted to him—as well as shocked and horrified to realize it—I spoke of it to no one, least of all him. I hoped I would go home and the feeling would go away. But it didn't. Instead, it grew. 
This is important. It is important for people experiencing GSA to be able to talk with someone about it without being treated like a criminal or somehow defective. However, even people who have had access to such support, have still gone on to have sex with their GSA partner(s).
It was August 2009, and one day, my dad did something that deeply upset me. The heat outside was deadly, and we stayed cooped up in his bedroom, where there was air conditioning. We were watching TV to pass the time when he put on a porn channel. Sex workers were being interviewed and he told me which of them he would most like to f---.
I fled from the room in anger and confusion. I shut myself up in the other bedroom, which was oppressively hot, until he coaxed me to come out, apologizing repeatedly. I wanted to love him. I felt I needed him in my otherwise broken life. But things were starting to feel wrong between us. He was crossing boundaries; I was doing my best to suppress my sexual attraction to him. But despite my sense of impending doom, it was there. And then, we became sexually involved
Nobody should do anything they don't want to do. It seems from the whole of what we read in these pieces that she was feeling very conflicted.
We had oral sex a few times, almost always preceded by my descending into a whirlwind of self-hate and disgust and dry heaving over the toilet in the bathroom attached to his room.
Again, if this was entirely due to an external pressure, then isn't that pressure the problem?
It took my therapist at the time explaining GSA to me, and that it is never the child's fault (a person, regardless of age, is always the child in their relationship with their parent), for me to stop blaming myself. 
I wonder if that's still considered to be so in cases in which the genetic parent is aging and to the point they are physically and/or financially depending on a middle-aged child they just met for the first time a few months ago? Is it still the parent's "fault" for not shutting down physical affection before it becomes sexual, when that is what both of them want? Putting aside any argument as to whether this particular case was consensual or not, "fault" is a strange word to use about consenting adults having sex.
To many people, parent-child incest is as repellent as pedophilia, to which it is linked in obvious and complicated ways.
Uh, no. Adults having sex with each other is in no way linked to, for example, a sports coach molesting a prepubescent child, any more than lovers sharing candy on Valentine's Day is linked to Mr. Burns stealing candy from baby Maggie, to use a much less serious example.
So here's a new story to throw into the mix: genetic sexual attraction is normal, and very real.
She has that right.
If it is a parent-child relationship, the parent, whether male or female, is always responsible for establishing and maintaining boundaries. Failing that, they are sexual abusers.
Only if some form of coercion was involved. Chenier is appealing to a child's desire for a parent, even if this parent was only a parent genetically. Because of that desire for a parent, she's saying even consensual sex between them is abuse. I'd like to know if she'd say the same thing about someone wanting to have a wealthy or famous partner? There are people with very strong desires to have such a partner. If they find one, are they being abused?

To follow this up, Jia Tolentino had an interview with Chenier at the same website.