For the avoidance of doubt, I agree, and the reason I did that calculation in the first place is that such a lot of the wall-space in my house is occupied by bo

For the avoidance of doubt, I agree, and the reason I did that calculation in the first place is that such a lot of the wall-space in my house is occupied by books. (But there are no rooms completely given over to books; instead the fiction is in the main bedroom, the academic-y books in the study, the humour in the guest bedroom, etc.) Our daughter reads a whole lot, but as well as growing up surrounded by books she has very bookish genes, and bookish friends, and a library two doors down the road, and so forth, so it's hard to disentangle the causes.