My nephew is 6 years old. Since DS was born, my nephew has been displaying what seems to be an unusual amount of curiosity about him (compared to my other nieces and nephews). And the way he interacts with DS just weirds me out and makes all kinds of Mommy Alarm Bells go off.
It's nothing horrible, but just stuff like playing with his diaper (while it's on him), wanting to watch diaper changes, and wanting the baby to put his mouth on various body parts - nose, elbow, etc. - you know, babies will chew on anything. Basically nothing untoward has happened, but for some reason all of my Mommy Instincts are saying don't leave LO alone with him.
I'm certain that my nephew has no bad intentions, but maybe he's just a little too curious? And sometimes a little too curious about parts of the body that aren't entirely appropriate to be curious about. I have heard of too many kids who were molested by cousins...
I'm not planning on telling my sister about this, just making it a point not to leave the baby around my nephew when I'm not there. Am I being completely nuts??? I feel awful to suspect that my nephew (who is weird but a decent kid) would do something to DS, but my #1 priority is my son of course.
Re: Mommy Instincts... cousin trouble?
ditto this. If something bad did happen to him or is happening to him you could be the one to stop it. I agree leave your feelings out of it but bring it to her attention. Her son is her #1 priority too
I am sorry you are dealing with this 
If something was happening to this little boy and you did nothing to prevent/stop it, how would you feel? What if the tables were turned and in a few years, someone felt this way about your child?
You need to talk to your sister in a kind and caring way about your concerns. Tell her you're probably overreacting.. but...
i agree with this. please say something to your sister. and always listen to your instincts.
all of this. My heart goes out to your family for having to deal with this.