Duplicate DNA

Picture from: wileywitch.com

For today’s post we've kept in mind the posts to come. We decided to shed some small light into the differences between identical and fraternal twins. 

There are actually seven, that right seven different kinds of twins, but for today we will stick to identical and fraternal as they are the most common and/or heard of.

For the sake of not have the world record on the longest post, we've tried to keep the explanations and terms as simple as possible. 

As a side note, we will be changing our posting days from Tuesday to Thursday. So keep a look out for this Thursdays post.

(Que drum roll) Let us begin the fascinating trip 
Take a moment to recognize these celebrities. Did you know they were twins?

Identical:
 

Jon and Daniel Heder

The fancy word is Monozygotic, but we'll refer to it from hereon-out as Identical twins. These sorts of twinsa come from a single egg and a single sperm combination that splits a few days after conception. They are special in the way that their DNA originates from a single source, hence their genetic makeup is the same. Identical twins are always of the same gender, except in extremely rare cases of chromosomal defect.

It’s not known how identical twinning occurs, but there are some theories. One theory states that since the rate of identical twins is higher in mothers who are either very young or very old, identical twins may be due to the hormonal imbalances seen at these ages. 

The rate of identical twinning (oh see what we did there?) is fairly constant in different countries and ethnicities, unlike the rate of fraternal twinning which is very different in different cultures and ethnicities; more on this later.
 The rate of identical twins remains about 1 in 250 across the globe.Having two sets of identical twins would be a rare occurrence. The odds of having more than one set of identical twins are at least one in 70,000.

Fraternal

Scarlett and Hunter Johansson 

The fancy word is Dizygotic, but we'll keep it real and say fraternal; usually occur when two fertilized eggs are released by the mother and both become fertilized by two different sperms. We've heard eggs could even be fertilized up to two weeks apart (that's cray!)

Fraternal twins have a very small chance of having the exact same chromosome profile, but most likely have a number of different chromosomes that distinguish them. These twins may be a different sex or the same sex. Like singleton siblings they share 50% of their DNA.




Fraternal twins do run in families. It is only the female that has any influence on the chances of having fraternal twins as the male cannot make her release more than one egg. It is dependent upon the woman carrying a fraternal twin gene and can also be affected by heredity, race, marital age and number of children previously born. Two-thirds of all twin births result in same sex fraternal twins and one-third are different sex fraternal twins. About two-thirds of all twin births are fraternal.
Interesting hey? We really enjoyed researching and finding out more information about the different kinds of twins; especially the more “unusual types” which we will be posting about in a few weeks’ time.

Once you have had fraternal twins, your chance of having another set of twins is three to four times more of the general population. Fun fact: The ability to conceive fraternal twins has ethnic differences also. Fraternal twinning is most common among African-Americans and less common among Asian populations.

Here are the links we received most of our information from: Twinsuk and Nomotc.org