Children growing up in abnormal families (i.e. all families) have a natural tendency to think that their home life is the norm. My daughter is baffled by people who haven't heard of David Attenborough or who can't name all the instruments of a Javanese gamelan, while one of Charles Darwin's offspring supposedly asked a schoolfriend "Where does your Daddy do his barnacles?"
A few weeks ago I was in the lobby of the local leisure centre waiting for my daughter to emerge from the changing room after her swimming lesson, and sitting next to me was a man on a similar errand, except that he had a three-year old boy to keep amused. He was evidently a keen fisherman, and was attempting to read a fishing magazine. "What's that Daddy?" asked the boy, pointing a grubby finger at a photo in the mag.
"That's a golden tench!" replied the proud Dad.
I safely predict that not only will the lad be able to name 100 types of fish by the age of 10, but will be baffled by anyone who cannot.