Kayah and Kumnos

well, as we should know, centaurs can't give birth in the shape of half human and half horse, the spine of a human baby can't sustain it's weight to stand straight, thus, the centauresses turn into horses (mares) and give birth to foals

3 years after the birth, the mares turn back to the centaur shape in front of the foal, it will instinctivelly turn into a centaur too by copying it's mother

here we have little Kumnos right after his transformation, and Kayah stretching out her human bones, 3 years is a long time to be looking like a full horse