This is the result of 200 years of inbreeding, Charles the II of Spain, at age 4 he could barely walk and was still breastfeeding. At age 9 he couldn’t read or write, he died at age 38 and his death led to the War of the Spanish Succession killing between 400k and 700k people.
“The king is rather short, skinny, but not badly formed, only ugly in the face; he has a long neck, a long face, a long chin and as if it bent upwards; the lower lip typical of the Habsburgs; not very large eyes, turquoise blue and a fine and delicate complexion.
He has a look with melancholy on his face and a little astonished. His hair is blond and long, and it is combed back so that the ears are exposed.
He cannot straighten, unless he leans against a wall, a table or something else.
His body is as weak as his mind. From time to time he shows signs of intelligence, memory and a certain liveliness, but not now; he usually looks slow and indifferent, appearing dumbfounded.
You can do whatever you want with him, since he lacks of own will”