Is it obligatory for a woman's mahram to be an adult of sound mind?

Question : Is my ten-year-old cousin considered a mahram for me, such that it is permissible for me to ride in a car with him and the driver?

Answer : Yes, the mahram must be an adult of sound mind. If he is a child, he is not sufficient for the status of mahram, and if he is insane, he is not sufficient. He must be an adult and of sound mind. Puberty is attained through three things: the emission of semen with desire, the growth of pubic hair, and reaching the age of fifteen years. If one of these three occurs, puberty is attained; if none of them occurs, there is no puberty. The mahram must be an adult of sound mind.