Final answer:
The provided passage does not disclose the exact age at which Maranda began having grand mal seizures, only that epilepsy developed in childhood or youth, and the exact age is unknown.
Step-by-step explanation:
The passage provided does not specify the exact age at which Maranda started having grand mal seizures. It mentions that the patient, presumably Maranda, developed epilepsy in his childhood or youth, but the exact age is unknown. In relation to the case of Ben Carson in Gifted Hands: The Ben Carson Story, if Maranda is a subject in the book, the text does not disclose her age at the onset of her seizures in the information given.
Later in the patient's life, specifically at age 30, the patient lost the ability to speak, resulting in admission to a hospital in 1840. This information suggests a medical history potentially relating to epilepsy or other neurological conditions but does not provide precise details regarding the age of onset for Maranda's grand mal seizures.