Since age plays such a big part in the story here, it is interesting that Sally Field and Janis Hansen are both several years older than the characters they are playing; Gidget claims to be 15 years old (Sally Field was actually 19 years old at the time); Della Mae doesn't reveal her age, but it is supposed that, as a student in college (it's safe to assume she is not a graduate student), she would be at most 22 years old (Janis Hansen was actually 25 years old at the time). On the other hand, Jeff's father and mother profess to be 45 and 40 years of age, respectively, ages that correspond to Hal March and Hazel Court's actual ages. And, while Professor Lawrence doesn't reveal his age, it's safe to assume Don Porter's age of 53 at the time fits his character's age.