Theodore Sturgeon The Synthetic Man (1950)
This being the second novel I've read by Sturgeon, I must conclude that biology, mutation, and outsiders were common preoccupations of his writing as this one also features a group of freaks trying to make their way in the world. It's been a while since I read More Than Human, and I can't actually recall much of it beyond this distinguishing feature and the fact of it being extremely well written, but the freaks of The Synthetic Man - the earlier novel for what it may be worth - have banded together for safety as part of a travelling side show. The pseudo-gothic freak show has become something of a cliché, and without really caring enough to look anything up, I suspect it's probably been trotted out by Clive Barker, Ray Bradbury, Neil Gaiman and others with some frequency - although I personally thought Lawrence Miles used it very well in Interference - but Sturgeon writes with such lively confidence that it feels like a new idea, which is pretty good going for something published over half a century ago.
Kiddo, as he is known, turns out to be something much stranger than the robot implied by the title - at least to me - as Sturgeon asks us to consider the possibility of there being another form of life here on Earth unlike anything with which we are familiar, thus far undetected because it has no effect on us, nor we on it. Further to this we get Kiddo growing up as female in order to elude the wrath of its misanthropic sideshow owner - not simply the bold use of a transgendered main character at a time when this would have appeared quite shocking to at least a few of the readers, but a main character who is transgendered for reasons of narrative and theme rather than as a simple example of the freakish.
Sturgeon writes well with the warmth and authority of someone who weaves tales, as opposed to simply filling pages and making a living from the pulps. For want of a better description it's van Vogtian surrealism communicated with the simple clarity of Ray Bradbury, and The Synthetic Man has been a real find. I really need to keep an eye open for more by this guy.