Twins Day is celebrated the first full weekend in August, in Twinsburg, Ohio. Its purpose is to celebrate the uniqueness of twins and other of multiple births, to provide a centralized location for twin-related information, and to provide an economic boost to Twinsville. Twinsday.org
Worldwide there are at least 125 million living multiples. Up to 22 percent of twins are left-handed, while in the non-twin population the number is just under 10 percent. Nigeria has the highest rates of multiples, with more identical twins than fraternal. China has one of the lowest rates, with multiple births occurring one in 300. babymed.com
Certain cultures consider multiple births a portent of either good or evil. Mayan culture saw twins as a blessing and was fascinated by the idea of two bodies looking alike. In Ancient Rome, the legend of the twin brothers who founded the city made the birth of twin boys a blessing, while twin girls were seen as an unlucky burden, since both would have to be provided with an expensive dowry at about the same time. Wikipedia
Disclaimer: The information on this website is accurate to the best of my knowledge at the time of writing. I make no guarantee as to its accuracy. Its purpose is to inform, educate, and raise awareness about causes and opportunities around the globe. I also encourage civil debate in the comments.