Very good point - I can see Ianto's restraint being his little rebellion, of a sort. I also completely see Ianto as an older child, though I'm not entirely sure why. I'm a middle child myself, so the mentality's harder to get at. -grins-

On the other hand, I could see Ianto's parents being ultra-strict - a little like Jack from Lost's, if you watch it. Ianto's behaviour then becomes an effort to be the 'perfect' son for his father. Of course, then Jack comes along and ruins that theory completely!

Either way, I'd say Ianto's parents would definitely be far from ordinary. :)