Flag families are sets of national flags with similarities in their design, often based on a shared history, culture, or influence. Families do not include flags with coincidental similarities. Flags may be in multiple flag families. Only twelve current national flags existed before the 19th century, when large-scale flag use began. Seven of these flags (Denmark, France, the Netherlands, Russia, Turkey, the United Kingdom, and the United States) are the inspiration for more than 130 current national flags and ensigns.[1]
...flag use did not develop on a large scale until the 19th Century and continued during the 20th Century. Out of some 195 independent countries, only 12 have flags whose designs were adopted before 1800. Seven of these (Denmark, Great Britain, the Netherlands, Russia, the United States, France and Turkey) have influenced the designs and colors of over 130 national flags and ensigns...