inappropriate behavior by step son
I have a 5 year old stepson, 3 year old son and 1 year old daughter. My step son came to live with us 6 months ago. he is mean to my 3 year old; he just walks by him and hits or kicks him for no reason. he also takes the toys and hides them.
The first thing I caught was the 5 year old was trying to put his privates in the 3 year old's face. we told him it was wrong and not to do those things. he kept saying he didn't do nothing.
then I caught him grabbing the 3 yr old and forcing him to kiss him. it looked like he was trying to make out with him. he also denied that and about 3 months later he did it again.
he also came out of the bathroom naked and was shaking his private and callin the 1 yr old girl. laughing and I am the one who catches him in these acts and when i tell his dad he tells me that is normal.
the 5 yr old also grabs the 1 yr old girl and hugs her and kisses her very aggressively until they fall to the floor and roll around and when she is awake he is laying on the ground he gets in front of her a lays on the ground he also tries to get them to go under the beds and in the closets and when I tell them no he gives me a dirty look.
he denies everything and tells his father that Im lying. can you please help me? I don't want to put too much into it but I'm worried about my kids: all 3 of them. Is this normal?