Is My Neighbor, Who Is A Registered Sex Offender, Allowed To Live With The Children Of His Girlfriend?

Not sure what flair to use for this post, but I have a neighbor who is a registered sex offender has a girlfriend that, as far as I can tell, is living with him and her kids also appear to be living there.

His crime happened 20 years ago. He was 27 and the victim was 15. He was convicted of attempted aggravated indecent liberties with a child, a felony, and he has to register for life. He is compliant with his reporting.

The particular child in question is about high school age and walks in front of my house on her way home from school every day. Today as I pulled into my driveway he was out greeting her and put his arm around her as they walked up to their house and it really icked me out and made me worry for her. I hope it’s nothing, but is he even allowed to live with kids that aren’t his? Should I be reporting this to someone so they can make sure everything is okay? I don’t know anything about his girlfriend, so I don’t know if he’s reported that he’s living with non-biological children. Does it even matter what age/gender the child is? I think it bothered me because she is around the age his victim was, would it be any different if it was a 4 year old boy?