This is a somewhat difficult question to answer, because in classic Roald Dahl fashion, the novel leaves this up to the reader's imagination. One conversation between Sophie and the BFG addresses this question. After the BFG takes Sophie from her bedroom, she finds herself in a giant cave. At first,...
This is a somewhat difficult question to answer, because in classic Roald Dahl fashion, the novel leaves this up to the reader's imagination. One conversation between Sophie and the BFG addresses this question. After the BFG takes Sophie from her bedroom, she finds herself in a giant cave. At first, she is convinced that he has brought her there to kill her, and she is very frightened. However, once he has convinced her fully that she is not in danger of being gobbled up (at least not by him), they begin to share stories and get to know each other.
Sophie soon comes to realize that the BFG has a peculiar way of speaking, and that his sentences often seem to get mixed up. When he is describing the revolting vegetable that he eats, the snozzcumber, he exclaims, "I squoggle it! I mispie it! I dispunge it! But because I is refusing to gobble up human beans like the other giants, I must spend my life guzzling up icky-poo snozzcumbers instead. If I don't, I will be nothing but skin and groans." Sophie corrects him, saying, "You mean skin and bones." The BFG gets quite upset, embarrassed by his lack of knowledge, and reveals that "There never was any schools to teach me talking in Giant Country."
Sophie is surprised by this and asks him, "But couldn't your mother have taught you?" to which the BFG replies, "My mother!...Giants don't have mothers! Surely you is knowing that!" as if it is an obvious fact. The BFG goes on to laugh at the idea of a woman giant and declares that all giants are men and always have been. Sophie, of course, is even further confused by this, and asks, "In that case, ...how were you born?" The BFG replies, "Giants isn't born...Giants appears and that's all there is to it. They simply appears, the same way as the sun and the stars."
When Sophie then inquires when he "appeared," the BFG again is confounded by the question, grumbling, "Now how on earth could I be knowing a thing like that?...It was so long ago I couldn't count...All I is knowing about myself is that I is very old, very very old and crumply. Perhaps as old as the earth." Sophie follows this up by asking, "What happens when a giant dies?" The BFG replies, "Giants is never dying...sometimes and quite suddenly, a giant is disappearing and nobody is ever knowing where he goes to. But mostly us giants is simply going on and on like Wiffsy time-twiddlers."
The BFG's explanation of the creation of giants implies that giants simply appeared around the same time that the earth was created. It is left up to the reader to imagine how they actually came to be.