My older sister, an honor student, was precocious and learned to masturbate early. The first time my sister made her brother lick her anus was in the summer when she was a school student and her brother was a student...Even after they became adults, this habit continued, and even though she had a boyfriend, she still couldn't give him anal cunnilingus. The older sister is no longer cool and goes into the forbidden realm, even asking for sex... A sister and brother who have the best physical chemistry.