As a kid I used to loosely know the family, not closely, but certainly enough for my parents and his parents to stop and chat if they bumped into one another.
I'm not sure how much of his demeanour is actually from lack of social contact and innocence, both Bindi and he were homeschooled and kept apart from local kids. Robert grew up in quite a feminine environment, without any bigger brother or particular male influence. In real life, the Irwin's are fairly reserved, as were the grandparents. A combination of that being seen as snobary and jealousy of their success internationally (they were never so big at home) over time has created some bad feelings between the locals and the family (especially Terri).
He's certainly a decent photographer. Although he wasn't known for it, his dad Steve was a very keen cameraman, the performance was just a means to an end that came about to save his father's business when it was about to collapse. His sister Bindi had a lot of behavioural problems, real Chucky doll, which he learned from and began to copy at a young age. Robert got given the camera to follow his dad and give him some focus. He's also a big skateboard freak which they got him into to burn up energy.
The Steve I remember was a smart, driven and very calculated guy - no clown. I get the impression Robert is quite like his dad, so I wouldn't read too much into his true self from his public performance. It wouldn't shock me if he does turn out gay, but he's pretty young.
