When he was in his teens, YS was very keen on animals, so eventually we had 13 rabbits, various mice, rats, hamsters, gerbils, chipmunks, chinchillas and probably many other small furry creatures that I have now forgotten about. (Notice I am not including the water snake in this, as that belonged to Elder Son.) Oh, and then there were the fish, lots of them in the huge pond that he constructed, so huge that I had to tread water whenever I hung out the washing.
However, the link to National Shed Week is that YS had three of them. Birthday and Christmas presents tended to be shed-related for a few years and, as well as providing homes for the multiplicity of small animals, they provided a valuable opportunity for him to learn and develop carpentry, building and electrical skills.
So, I hear you surmise, he's probably got his own pet shop by now. Well, actually no; he works in an office. But he does have an allotment, presumably with at least one shed on it.
Funny how things turn out...