Twins 101

I certainly have been doing a lot of learning about twins!

I thought it would be fun to put together some of the info I have collected over the last five months:


Identical Vs Fraternal

Identical twins occur when a single fertilized egg splits and develops into two fetuses. Identical twins may share a placenta, but each baby usually has a separate amniotic sac. Genetically, the two babies are identical. They'll be the same sex and look exactly alike. They have the same DNA and will have different fingerprints. Only one-third of twins are identical. The chances of having twins that are identical are approximately 1 in 250 or 0.4%. It is unknown as to why a fertilized egg splits to form identical twins. Identical twins do not run in families and there is no way to increase the probability of having them.

About 25% of identical twins are called mirror image twins. For example if one has a mole under her right eye, the other will have it under her left eye.

Fraternal twins occur when two separate eggs are fertilized by two different sperm. Each twin has his or her own placenta and amniotic sac. The twins can be two girls, two boys, or a boy and a girl. Genetically, they're no more alike than any other siblings.

Twins Info

The average length of a twin pregnancy is 36 weeks and 3 days.

The average weight of twins at term is about 5.5 lbs.

22% of Twins are left handed, where as in singletons only 10% of them are left handed.

In case of identical twins marrying identical twins, genetically speaking their children will be more than cousins, they will be genetic siblings.

It is possible for a woman to become pregnant from two different men and give birth to fraternal twins.

Women pregnant with twins will have more ultrasounds, tests and prenatal appointments than women pregnant with singletons.

Famous parents of twins:
Cleopatra
Angelina Jolie and Brad Pitt
George Bush
Jennifer Lopez and Mark Anthony
John Wayne
Julia Roberts
Lance Armstrong
Nikki Taylor
Sarah Jessica Parker and Matthew Broderick
Louis XV, King of France
Margaret Thatcher
Mel Gibson