would you be worried?

[imawigglyworm]

Ds2 8yrs (ADHD/SPD) has been showing some inappropriate behaviour lately.
Ds1 has just walked in and witnesses ds2 putting/rubbing ds3 6yrs head on his genitals (ds3 is also SN gdd/rare genetic disorder/non verbal so no understanding of what happened). He's admitted it to me but doesn't know why he done it.
We've again had to have the 'it's inappropriate- do not do that' talk.
He's shown concerning behaviour before smearing, playing with what he's done in the toilet, 'accidently' touching his brothers & dads privates - they've both said that it doesn't always seem accidental, staring - a little too long whilst people are changing or his brother is having his nappy changed etc. I know children are curious but some of his behaviour just seems a little more than that.
Would you be worried? Why could he be doing it? Do I need to continue to drum it into him that this behaviour is wrong or am I doing something wrong?
I feel really bad thinking anything bad about my ds :-(

I didn't want this to remain without an answer so I hope that you see this.
I have an 11 year old who operates on his own plain of existence. While I haven't seen behavior quite to the degree you have he likes to lie on top of his 6 year old sister, excessively hug and do the staring. I do feel a bit uncomfortable about it but I think it is my issue more than anything. I think it is based in complete unawareness of social boundaries and difficulty with impulse control. I also think that the SPD plays into it - our DS makes sense of his world through touch at the same time as being tactile defensive Like you we give clear instructions of appropriate behaviour and use social stories as a means to discuss healthy touching and relationships. We also reinforce appropriate touching "You can't lie on dd but you can lie beside her and hold her hand" This can give him appropriate boundaries to fulfill his needs while still keeping both of them safe. We still need to redirect the behaviour alot as he hasn't yet begun to self regulate in this area but I am fairly confident he will as he has the cognitive ability to understand what we are trying to teach him he just lacks the maturity and control to apply it yet.

Thank you for your reply.
I do wonder if it's the way I look at the situation sometimes, it's so hard to know what to do for the best sometimes :-/
I completely agree I don't think DS is certain of boundaries and personal space so he can struggle socially at times too so maybe he just needs to develop a bit more in these areas.
Looking online it seems that these behaviours still fit 'within the expected norms'