Horses are born with the whorls that they will have for life. That can give us a good clue about temperament from birth.
Head shape can get a little more complicated.
Foals are born with a bump over the forehead. This is the horse equivalent of the soft spot in a human babies skull. As the foal grows and matures the baby bump will go away allowing us to more clearly see what the head shape will truly be. If we pay too much attention to the bump we will get misleading ideas about what temperament will be like.
It’s important not to confuse this baby bump with a ‘jibah’, or bump in the forehead that adult horses have showing an emotional reactive horse. The dish to the profile caused by the baby bump is also not permanent or a true indication of character.
It is best to wait to look at head shape in a foal until they have matured to the point that the baby bump has grown out and the head is showing its true shape.