Icon and singer Beyoncé Knowles just posted today on her Instagram that she is pregnant and with twins. "We are incredibly blessed that our family will be growing by two, and we thank you for your well wishes," she wrote in the February 1 post with her photo, which was signed "The Carters." Beyoncé is married to rapper Jay Z. They already have a 5-year-old daughter named Blue Ivy.

Here Are Some Facts About Having Twins For The Expectant Star

Twin birthrates are at an all-time - The U.S. twin birthrate reached a stunning record high since 2014, according to the latest data from the Centers for Disease Control and Prevention. In 2014, there were an average of 33.9 twins per 1,000 births, up from 33.7 twins per 1,000 in 2013, as CDC found. And the "twinning rate" has doubled since 1980, when there were 18.9 twins per 1,000 births, according to historical archives.

One common reason for twin birthrates increases is that women are engaging with fertility treatments more, such as in vitro fertilization, which can increase twin pregnancy, according to the CDC report. In fact, women are having children at a later age, which may also increase chances of having twins, the researchers wrote.

• Identical Twins Aren't Identical - Indeed, they are genetically different. Although identical twins start out with identical DNA from the mother, genetic changes can occur very early in fetal development, per research shown in a meeting for the American Society of Human Genetics. These genetic changes may partly describe why some sets of identical twins go on to developmental stages differently while growing - for example, one twin may get cancer while the other stay very much healthy.
• But Their Genes Do Play A Big Role - Researchers of The Minnesota Twin Family Study - on identical and fraternal twins who had been separated at an early age, discovered that even after living apart for decades, the twins still had a striking number of similarities, both medicinal and emotional. The findings highlight the power of a person's individual genes. For example, even after living apart, identical twins would stand in the same way, while fraternal twins stood up in different positions. One famous twins in the study, are the identical twin brothers Jim Lewis and Jim Springer who were separated when they were 4 weeks old, and reunified at age 39. It was then that they discovered they both got tension headaches, bit their nails, smoked the same brand of cigarettes, and drove the same type of car.
• Twins May Live Longer - - Twins appears that they can live longer than ordinary men and women who aren't twins. The research found out, from Denmark, that identical twins may live longer than fraternal twins, and both types of twins live longer than ones. Precisely, identical twins lived, about on average, 4 to 5 years longer than those without a twin. Fraternal twins lived, on average, 2 to 3 years longer than those without a twin.
• Twins Run In The Family - - The basic reason why some women have twins while others do not could simply be because of these two genes, according to a study from the Netherlands.

Researchers have long-known that women are more likely to have fraternal twins if other women in their family have had fraternal twins too, but it was unknown if any genes were involved.