Carlos The Betwitched is actually a fascinating character to read up on.
https://en.wikipedia.org/wiki/Charles_II_of_Spain
Charles was born in Madrid to Philip IV of Spain and his second wife, Mariana of Austria. The only surviving son of his father's two marriages, he was named Prince of Asturias, a title traditionally held by the heir to the Spanish throne.
Philip and Mariana were uncle and niece, making Charles their son, first-cousin and great-nephew respectively; all eight of his great-grandparents were descendants of Joanna and Philip I of Castile.[a] The impact of this inbreeding is not fully understood; his elder sister Margaret Theresa does not appear to have suffered disabilities as he did.[2]
Charles himself was severely disabled, both physically and mentally, described as "short, lame, epileptic, senile and completely bald before 35, always on the verge of death but repeatedly baffling Christendom by continuing to live."[3] He is thought to have suffered from the endocrine disease acromegaly and a combination of rare genetic disorders often transmitted through recessive genes, including combined pituitary hormone deficiency and distal renal tubular acidosis.[4] In his case, the so-called Habsburg lip was so pronounced he spoke and ate with difficulty his entire life. He did not learn to talk until the age of four, walk until eight, was treated as an infant until he was ten and did not attend school.