This case study in human reproduction follows Andrea, a college biology student who discovers she is pregnant with twins, but is not sure who the father is. Students are presented with a variety of signs, symptoms, and physiological information that they interpret by researching and answering a series of questions. Students gain an understanding of female reproductive cycles by investigating this unusual pregnancy. Students also discuss the importance of safe sex practices and contraception. Developed for an undergraduate general biology course, the case also could be used in women's studies, human health and sexuality, or advanced high school biology courses as well as upper-division anatomy and physiology courses. There also is an opportunity to discuss the biotechnology involved in DNA/paternity testing (DNA extraction, enzyme digestion, and gel electrophoresis).