The 'fun' of maths isn't the same fun as you get from, say, playing another game of some casual computer game where you're simply switching off and doing something relaxing. It's fun in the sense that it's a challenge and provides immense satisfaction when you work out problems with it.

I've noticed that I get a rarely-rivaled sense of satisfaction when I see different bodies of knowledge that I've covered come together. For example, if my physics from school/uni help me solve a problem I'm facing at work, it gives a really good, satisfying feeling of mastery over the topics at hand. Deriving a solution without guidance, simply from your own existing knowledge, is a wonderful feeling.

The problem with this is that unless you embrace that 'inquisitive for inquisitive's sake' attitude, you don't easily justify fully exploring subjects like maths to the point of gaining that capacity. It's the same as programming, just as you touched on. Someone could be a moderate programmer if they learn what they need to spit out basic code to achieve an end goal, but you won't feel the same satisfaction of mastery as if you embrace the art and program things 'just because'.

The good thing is kids seem to be born with this attitude innately - just look at any young child explore the world around them. It's only really through social conditioning that it seems to be beaten out of them, as you say. Through good role models and leadership (e.g.: from teachers, parents) providing adequate material to feed that curiousity, it can be avoided.

It's fantastic that this kid's parents are willing to do what they did, just as your mother was willing to feed your curiousity. Understanding how significant it can be to the development of a child throughout their life is, I think, the key to fully appreciating the role that teachers (formal and informal) have in our society and why they should be valued far more than they often are at present.