Are they identical?
Identical twins occur when one egg is fertilized by one sperm. The egg divides, producing two individuals. Identical twins are always the same sex. They look alike. Both will have straight or curly haird, the same eye color, etc. Fingerprints are similar, but never the same. Placenta examination to determine if the twins are identical is not always accurate. Blood testing is more efficient and reliable. DNA testing is the most accurate, and most expensive way to determine twin type.

Are you sure they're twins? They don't look alike...
Fraternal Twins are the result of two eggs being fertilized by two separate sperm. They are no more similar than any two brothers or sisters. Fraternal twins may be boy / girl or same sex. They may look alike or very different. Only fraternal twins tend to run in families. Identical twins happen by "chance" and can happen to anyone, regardless of whether there are twins in family or not. Your own chance of having twins depends on your personal history, age, race, fertility treatments, number of pregnancies, social habits, geographic location, seasons, nutrition, and other factors.

More than half of all multiple births in the United States are low birth weight. Less than 5.5 pounds. Also, more than half of multiple births are born before the thirty-seventh week and are considered premature.

For more information on twinning go to:
National Organization Mothers of Twins Club