I’m scared to leave my toddler alone with my wife’s nephew

Throwaway because I don’t want this tied to my personal account, but this has been gnawing on me for a long time and I need to get it all out.

Important context: one of my earliest memories is of a (then) male friend of the family CSA me. Because of this I am not the most trusting towards men and I do have CPTSD today. However, it is being managed and I’ve been out of therapy for 10+ years and medication free for roughly 9.

A bit of background: My wife has 3 nephews that I’ve known from they were born. They have a troubled home life and all 3 deal with some serious challenges ranging from autism to speech impediment to depression to difficulties with mentalization. The oldest nephew, let’s call him B, is in his early teens. He’s a smart kid, charming. He’s skilled at finding the easy way out and has pretty much no respect for authorities, rules or consequences.
We don’t see their family too often as they live quite a way away from us, but we do see them several times a year.

My wife and I have a daughter who is now almost 3. Whenever we spend time with my wife’s sister and her family, the boys are very attentive to our daughter and she loves spending time and playing with her big cousins.

So. Quite quickly after my daughter was born I started having these… doubts, for lack of better word. Something told me I shouldn’t leave B unsupervised with our daughter. I couldn’t put my finger on why I felt this way or where this inkling came from, but it was crystal clear to me.

Time went on and B was only ever careful with our girl. He was very attentive to her and it was quite hard to make him understand that while he was still a tween and she was an infant, he wasn’t allowed to pick her up and carry her around. He was very interested in her development and would ask about when certain milestones would likely be reached such as cognitive memory or walking etc.

Nothing stood out as the reason my alarm bells were ringing. I attributed it to my past and felt extremely guilty that I’d even entertain these thoughts. I mean, I’d known this kid his entire life and out of the 3 nephews, he’s the one I have the easiest and deepest conversations with. It was very clear that it was mutual as he has sought out my company numerous times (and still does), like when I’d walk the dogs alone to get out of their chaotic house and he’d ask to join.

One day while visiting them, my wife and I decided to take our daughter for a walk with the dogs. As usual B asked if it was okay if he came along and of course we said yes. We chatted about this and that and once again he asked about baby development. This day, he was quite interested in what age babies generally start remembering things.
We explained it’s hard to say anything specific, but a rule of thumb is roughly around 3 years old. He seemed almost excited and said: “that’s great, so you can do whatever you want to her and she won’t even be able to remember it, as long as she’s below the age of 3”. You could hear a pin drop. My blood ran cold. Both my wife and I rushed to explain that even though she wouldn’t necessarily be able to remember episodes the way we would, even babies will react to traumatic events and there will be clear signs in their development. He still kept talking about how she wouldn’t remember anything so whatever we did didn’t count.

At the end of the walk, both my wife and I had exhausted all ways we could think of to explain to B that this is not an okay way to think of it and that babies and toddlers do still remember emotions and trauma related to certain people or places, and that you couldn’t and should never do anything to people while they’re unaware (be it asleep, drunk or before they have what we consider “memory”) that you wouldn’t want them to know about in an aware/awake state.
He didn’t seem to agree or really care much about our explanations which made me even more uncomfortable. But he was roughly 12 at the time and this could just be his mentalization issues showing and his still developing brain rambling, right? He hasn’t mentioned this since and over time I stopped thinking about this episode.

Anyway. The kids grew and so did my feeling that I shouldn’t let B alone with my daughter. Still, nothing ever happened that would warrant these feelings or thoughts, but whenever we were with their family, I’d keep an extra eye on my daughter and made sure she was never in any of the boys’ rooms without a parent. Not that I didn’t trust the other 2 nephews, but I don’t want to treat any of them different than the others. I never mentioned anything to my wife about my gut feeling.
I still felt shitty that I didn’t trust this boy. He still hasn’t done anything to deserve my mistrust and I’d never had this distinct feeling regarding any other man, woman or child in our lives, even though my CPTSD does make it harder for me to be totally carefree when it comes to letting anyone watch our daughter for instance.

Then a couple of months ago, my wife’s sister’s family visited us for the weekend. We see them way less these days because of unrelated family drama from the boys’ mom’s side so it was a tad strained. The weekend was quite nice all things considered. The boys played with our daughter, we all played games, we went to the park. Normal weekend. And yet that damn feeling got stronger. I do not want B to be alone with my daughter. Not even 5 minutes. Period.

The day after the weekend, my wife and I are in the car and she’s more quiet than she usually is. After driving some time in silence, she takes a deep breath and goes “I have no reason to say this. And i have no evidence or actions to back this up. But I would like to ask you that you never let B and our daughter alone together, not even for a moment”. I was equal parts relieved and freaked out that I wasn’t the only one with that feeling.
I told my wife that I had the exact same feeling. That I’d had it for ages and that I didn’t know where it came from or why. And she said for her it got really strong after that walk where he talked about being able to do whatever to babies as long as they were below the age of 3. Until that point I had somehow blocked that convo totally out, but I remembered every bit when she mentioned that.

We talked for a long time about that feeling. That completely unfounded feeling that had come to the both of us independently.
My wife also asked me if I’d ever seen B feel bad about any of his actions or sorry for other people. If I’d ever seen him exhibit any kind of empathy. This threw me for a bit, but I realised I haven’t. Coupled with his complete lack of respect or fear of consequences and punishment… I don’t know how to compartmentalise this.

I’m in part relieved that this isn’t just me. But it also makes it way more scary that my level headed wife has the same feeling, and strongly enough that she voiced it to me.

I have no idea what to do with this feeling. Is it trauma speaking? Am I being completely unfair to an innocent teen? Is it my intuition that I should absolutely not ignore, not even for a second?

TL;DR: my wife’s nephew has no respect for rules or consequences and doesnt really show empathy. He has talked about how you can do whatever you want to kids below the age of 3 cuz they won’t be able to remember, and has always made me feel like I should never leave him alone with my toddler. I never told my wife that. But she recently confided in me that she doesn’t want me to leave her nephew alone with our daughter.

Sorry for any grammatical errors and whatnot, English is my second language.