There are actually seven different types of twins: Identical, Fraternal, Mirror-Image, Polar Body (Half Identical), Mixed Chromosome, Superfecundation, and Superfetation.
20
Forty percent of Americans have never visited a dentist.
33
According to a study, women ages 22 to 30 with no children and no spouse earned a higher median income than comparable men in 39 of the 50 largest U.S. cities in 2008.
9
Yawns are more contagious among people with closer relationships.
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