Those attending a suburban Philadelphia high school commencement ceremony this month will see a lot of familiar faces: the school plans to graduate no fewer than 14 pairs of twins.

The 2014 graduating class of William Tennent High School in Bucks County includes five sets of male twins, seven sets of male/female twins and two sets of female twins, the Bucks County Courier Times reports.

Principal Dennis Best said he is not surprised by the number among the 485 graduates - he sees it every day while walking the corridors. Federal officials said the twin birth rate rose 76% from 1980 to 2009. Researchers have attributed the increase to growing use of fertility drugs and treatments and more births to older women.

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