Twin Zygosity DNA Test

Twin Testing - Many births in America result in twins being born, some are identical and some are fraternal.

Identical twins are formed when one egg is fertilized by a single sperm cell which divides within the first few days of conception. If division of the egg occurs after 8 days, this may result in conjoined twins, also known as Siamese twins. Twins conceived by this process are referred to as identical since their DNA sequence is identical. While the twins are identical genetically, this often does not apply to their actual physical or behavioral traits. Generally their traits are similar, however they can differ.

Fraternal twins are formed when two eggs are independently fertilized by two sperm cells. Fraternal twins do not have identical DNA but will have half of their DNA in common, just like siblings of the same parents who are born at different times. Fraternal twins may either be same sex or different sex. Occurrence of fraternal twins varies globally, and is more common in older women's pregnancies, women of African heritage; but somewhat rare among women of Asian heritage.

Twin classification at delivery often results in misidentification; many identical twins have two sets of chorionic membranes. Therefore, until a DNA or other blood test is performed, it is difficult to accurately determine whether twins are fraternal or identical.

Fees for this test include 2 individuals, and Paternity Express results are available 2-3 business days after receipt at the laboratory Relationship Testing Performed By An AABB Accredited Laboratory