First, read the English article below.

Not so high.  But you are probably not average.  If you have any of the below, your chance increases.  If you have a lot or all of the below, your chance increases a lot.  Conversely, if you are a young, underweight female of Asian descent with no twins in the family, the chance of twinning will be extremely low.  Having twins "in the family," particularly on the mother's side.  If you already have twins, your chance increases at least 4x. Being of African descent makes the highest chance of having twins, followed by European descent.  Hispanic and Asian people have the lowest chance of having twins. Being tall and/or well nourished or even overweight. Having prior pregnancies.  Women with 4 or more pregnancies increase their chances of twins dramatically.  It seems that the body is more likely to have twins after it knows you "can take it."  Many of the families that have a dozen children or more, show increasing numbers of twin births as they have more pregnancies. The older you are, the more likely you are to have twins.  If you are around 40, your chance is substantially higher, around 7%. At 45, if you can get pregnant, the odds are about 17%. Older women are most likely to get IVF, see below.  IVF also increases your chance of twinning. 

Now, please write a short abstract for it in Vietnamese. Abstract:
Hiểu rằng cơ hội mang song thai với một người bình thường là khoảng 3%. Hiểu rằng phụ nữ lớn tuổi ít có khả năng CÓ thai nhưng nếu có, họ có nhiều khả năng mang song thai.