My fetish is being a Caregiver/Daddy Dom/DDlg with incest play.
For me it's pretty straightforward. My 12yo sister molested me from when I was 6 until I was 8. She had been molested by an uncle before that.
We were in a very religious household that didn't ever talk about sex (not even to inform me that I was growing hair because I was hitting puberty), so I knew I couldn't ever talk about it. I was deeply ashamed and worried that my parents would disown me if they knew what happened. I actually had a memory block until I was 17 when my sister told my parents about it and they confronted me, at which point I had a whole other breakdown.
I didn't really realize I had the fetish until I was 19 and went to buy pulp written porno mags, and accidently (or unconsciously?) bought a two-pack with an all-in-the-family theme. It was terribly written, but the stories of mothers fucking sons and fathers fucking daughters turned me on so much I ended up getting super horny, jacking off a bunch and then afterward so ashamed that I threw it in a back alley dumpster so no one would know I had it.
Fast forward into my 20s and internet porn, and I found asstr.org and stories that fit my fantasies. I also started going to therapy to deal with my shame around being molested and basically fantasizing about it. I was also really slutty, but I would also disassociate during sex and go into incest fantasies to stay hard.
Fast forward to my mid-thirties. I was at the point of telling my long-term partners about it, but they were't into it. I got married, and my wife actually shamed me about my strange desires. We divorced and I moved to a big city and signed up for Fetlife. Finally at the age of 35 I was having the kind of sex I wanted. Since then, I haven't had any deep romances, but I've had sex with 3 other lovely (and hot) ladies who are very much in to what I'm in to. They are also very patient with the disassociation, and helping me get grounded and in my body so I can actually enjoy it to the point that I've actually enjoyed vanilla sex too. I'm not how to date any more (it's hard to find cross over between my kinks and people I'd fall in love with), but it is so so much better.
If you're struggling with your kinks, I'd recommend finding a good and very open minded therapist if you can. It did me a world of good.
A few things -- I'm not into children or real incest and as a survivor of childhood sexual abuse I'm absolutely against harming children by introducing sexuality to them. There are plenty of grown adults of every gender and orientation that are into this. Most of my partners have somewhat similar stories -- lots of anxieties about something that happened as a kid/teen and a desire to go back before life was so hard.
TL;DR Daddy Dom and Incest play to relieve the stress of childhood abuse, a long process of unpacking all the shame and a happy kinky ending.