(CBS/WBBM Newsradio) — New Trier Township High School’s sophomore class has people seeing double – at a record rate.

Five years ago, Ryan Novosel of Wilmette and his twin brother, Luke, were paging through the Guinness Book of World Records when they found the record for sets of twins in one grade of a single school.

Their Wilmette middle school class of 23 sets easily eclipsed the old record of 16. They promised to update once they enrolled at New Trier High School.

Now, the sophomore class has 44 sets of twins and a set of triplets, for 45 multiples (another record earned). Eleven twin sets are boy-boy, and 19 sets are girl-girl; the triplets likewise are all girls. Two families have two sets of twins.

The Novosel family collected the required documentation from each of the families, including birth certificates.  Verification by Guinness took a year.

They are an eclectic bunch.  Two sets were born on different days.  One pair differs in height by seven inches.  Some were born as much as three months early, while others were born late.  One set of girls weighed more than 15 pounds together at birth, while Luke and Ryan weighed less than two pounds apiece.

Most are fraternal, rather than identical, sets of twins. The three identical sets are all girls.

The Novosel twins’ mother, Nancy Novosel, says scientific studies suggest several leading factors in multiple births: maternal age, education, affluence and access to fertility treatments.

The Novosel twins agree on one thing: It feels good to have a twin who always has his back.