The case of phineas gage suggests that the lobes regulate our personality. these lobes are largely responsible for much of what makes us uniquely human.

Frontal Lobe

Explanation:

The structure of the brain is divided into four lobes namely: frontal lobe, occipital, temporal and parietal lobes.

The lobe in the front or frontal lobe is situated in the front portion of the cranium and  is highly vulnerable to the injury. The front lobe is associated with the emotional control and personality traits like it controls the motor functions, social and sexual behaviour, language and memory.

Since the frontal lobe controls the social and sexual behaviour, therefore, the frontal lobe is correct.

Thus, Frontal Lobe is the correct answer.