Shield is my 1st boy dog ever. I was worried about that too at first.
The vet was guessing he is 2yr olds & he isn't neutered but will be next week. He has been really good. He hasn't humped anything. **hooray**
So, i guess you never know like another poster said!
Another poster said a bored dog may, Shield is pretty busy with us, we are a busy household so maybe that helps?? I don't know.
GOod luck though, it isn't something that they will definitely do though. My girls have never done it either though.