You don't need a big brain, or a high IQ, to have a comfortable life and a good family.
Witness the case of this French civil servant, written about by Dr. Lionel Fuillet in The Lancet.
At age six months he was treated for hydrocephalus (water on the brain) with a shunt in his head to drain away the fluid. At age 14 he complained of unsteadiness and left leg weakness, which cleared up after the shunt was adjusted. Beyond that his neurological development and medical history were normal.
At age 44 the leg weakness returned and he was treated by Dr. Feuillet and colleagues of the Hôpital de la Timone and Faculté de Médecine, Université de la Méditerranée, Marseille, France.