The birth of twins has been a big event since ancient times. However, they were greeted with mixed responses from one culture to another. Twins were seen as a good omen in some countries, such as Nigeria, where they were greeted with celebration, and the twins themselves are still honored today with a yearly festival. In cultures where twins were considered bad omens, they did not fair as well.

The incidence of twins in the U.S. is about 1 in 80 births. The rate is 1 in 20 in Nigeria; this gives them a lot to celebrate. If you are a believer in natural selection, twins are more likely to have twins and this society selected out twiners and kept them fed and healthy. So, over the centuries they now have a very high rate of twining. Fraternal twinning (twins from two eggs) is inherited, some families ovulate more than one egg a month. The difference in the overall twin rate from one area to another is accounted for by fraternal twins or

non-identical twins. Several things effect the frequency of fraternal twins. Women who are older than 35 years old, women with previous twins, or with a family history have an increased rate of twinning. Of course, fertility drugs increase the rate as well. Fortunately, malnutrition decreases their frequency.

Identical twins are born at a rate of 1 in 250; this is fairly constant throughout the world. This type of twin starts with one fertilized egg that divides in two.

For Obstetricians, twins are more challenging. They are ten times more likely to have problems at delivery. They are 12 times more likely to be premature and also have a higher rate of birth defects and miscarriage. Cesarean sections are also more frequent. The potential is fabulous though: two minds and two hearts to shape the future. Twins are very, very special.