Because Asians have a creative life style.
It is called a "Irish Twins" when siblings are born within the same calendar year but have different birthdays.
siblings
Siblings born on the same date but different years are called "Irish twins." This term is used colloquially to refer to siblings born within one year of each other.
Twins who develop in separate amniotic sacs are known as dizygotic or fraternal twins. This means they were conceived from two separate eggs fertilized by two different sperm cells. Dizygotic twins can have different genetic makeup and are no more similar than siblings born at different times.
Two siblings born in the same month and on the same day, but in a different year are simply called 'siblings.' If they both were born on the same month; day and year they would be twins.
Non-identical twins, also known as fraternal twins, result from the fertilization of two different eggs by two different sperm. They are genetically no more similar than regular siblings, sharing about 50% of their DNA. Non-identical twins may or may not look similar, just like any other siblings.
Every sibling will loook different unless they are identical twins
Twins who are of the opposite sex or do not look alike are fraternal twins ~ not identical. This means that at the time of their conception ~ two eggs were fertilised. In the case od identical twins, one egg is fertilised and split in half.
No, you shouldn't need to raise them any differently. Fraternal twins are no more alike than two siblings...i know from experience that most twins like to be treated as, well...not twins. When you think about it, all they really are is siblings that are born at the same time. If you had a son who was 8, and a daughter who was 12; fraternal twins would be no different to these two siblings if they were both 8 or both 12.
fraternal
yes they are twins and siblings too at that.
Siblings can be the same age, in the form of twins and triplets, and other various forms of the multiple births.