There are two types of biologist, and they can often be identified from early childhood: the naturalist and the experimentalist. The naturalist thirsts after the names of animals and plants, even according their Latin tags an almost religious significance as if "Ranunculus" or "Tyrannosaurus" were the entry key to a secret society. The naturalist revels in the complexity and abundance of nature, and soon learns a huge roster of species names: the young Charles Darwin could not get enough of beetles or barnacles. The experimentalist, on the other hand, strives to get below the surface of nature, to find how animals and plants really work beneath the frippery of their taxonomy. Biodiversity becomes almost a distraction, because the real business is to find the right experimental organism, and then perform the right experiment on it. That's real science.

Richard Dawkins is assuredly a biologist of the second type. But this memoir takes us only as far as the man who wrote The Selfish Gene; it does not lead us into his later life to discover how he took on God.

Dawkins's account of his early years is surprisingly intimate and moving. His was the kind of childhood we might all dream of. His father was a botanist, and certainly also a naturalist, like many Dawkins relatives, and the early years were spent in the best bits of Africa, wandering through the bush with animals, in the company of caring friends and a sprinkle of servants. Dawkins's mother is delightfully described – and both mother and father introduced young Richard to the poetry that remains his pleasure. But he freely admits he didn't catalogue and collect a thousand species – in that regard, he was a disappointment to the Dawkins family naturalist tradition. I wonder if happy childhoods produce scientists, while fraught families turn out novelists? I am sure that the mature Dawkins could devise a statistical test to prove it (or otherwise).

Angst of a manageable kind did appear during Dawkins's prep school years and later at Oundle School. It might seem odd that he did not shine incandescently at school – but then shining was confined to sporty types in that milieu. Peer pressure and even bullying tended to make mediocrity respectable: childhood cruelty is something Dawkins evidently abhors, though it is so widespread it presumably has some explanation under the banner of evolutionary psychology. But there was one inspiring teacher at Oundle who put the young scientist on the road to zoology and to Oxford, where he has spent more or less his whole life. Before he was 17, he had disavowed an earlier and evidently strong Christian faith, which a devotion to scepticism replaced in spades.