How to Know if Twins are Identical or Fraternal

It can be hard to determine whether twins are identical or fraternal. Fraternal twins occur when a woman ovulates 2 eggs during 1 cyle and those eggs are fertilized by 2 separate sperm. This results in twins that have different DNA. Identical twins occur when 1 fertilized egg splits shortly after conception, resulting in 2 embryos. Identical twins share identical DNA because they originated from 1 egg and 1 sperm. Knowing for certain whether or not twins are identical or fraternal is not necessary, but many times parents and twins want to know. Here are some ways to know for certain if twins are identical or fraternal.

Instructions

Difficulty: Easy

Things You’ll Need:

• Ultrasound results during pregnancy
• DNA test kits

1. Talk to your ultrasound technician during pregnancy and find out what type of twin pregnancy you have. If you have twins in the same amniotic sac and only one placenta, then the twins are always identical. This type of twinning is rare and occurs only with identical twins.
2. If your ultrasound shows your twins are separated into 2 amniotic sacs, ask the technician or doctor what type of twinning you have. If there are 2 placentas and 2 amniotic sacs, the twins could be fraternal or identical. If there is 1 placenta and a thin membrane separating the amniotic sac into 2 compartments, the twins have a high probability of being identical, but there is still a chance they could be fraternal.
3. If your ultrasound shows that your twins could either be fraternal or identical, wait until they are born, and ask the hospital what their blood types are. Hospitals always blood type newborns.
4. If your twins are different blood types, you can know for certain that they are not identical.
5. If the twins have the same blood type, look alike and are the same gender, but you had a type of twinning during pregnancy that could result in either fraternal or identical twins, the only way to know for certain if they are identical is to have a DNA test done.
6. Search the Internet for labs that offer DNA test kits for twins. The labs will send the kits to you, and you will just swab the inside of the twins' cheeks for DNA. You send the kit back in and get the results back from the lab. The results will be able to tell you with certainty if the twins are identical or fraternal.

Tips & Warnings

• Shop around and compare prices when searching for DNA kits. There is a huge variation in price.