Which Twin Is Older? Should You Tell Them & Potential Impacts

The twin who is born first is known as the firstborn.

It doesn’t matter whether twins are born vaginally or by C-section; the first one out of the womb is considered the oldest. 

According to psychologist Michele Goldman:

“Twins will typically not be raised according to chronological birth order, especially if they are only a few minutes apart, but psychological birth order might still form over time.”

I have a close relationship with many sets of twins, including my own twins and my husband and his twin sister, and they have never expressed feeling “older” or “younger” than their twin based on who was born first. 

They feel equal to their twin, and any psychological birth order ideas they develop come from their place among their other siblings, not with their twin. 

Which Twin Is Considered Older

The most prominent belief in Western culture is that the oldest twin is the one who makes it out of the womb first.

The first baby born technically entered the world earlier than their sibling, so they are the oldest. They may be older by seconds, minutes, hours, or days.

Some people consider gestational age to be the true age and will try to figure out which twin is “older” based on implantation and gestational measurements.

However, this is tricky and sometimes impossible to accomplish. 

In other cultures, there are various legends and beliefs around twin birth order. 

There is an old Nigerian legend that says the oldest twin pushes the youngest twin out of the womb. Therefore, the firstborn is actually the younger twin. 

Also, Nayarafolo people in the Northern Ivory Coast believe that the second born twin is actually the older.

This belief is based on the reasoning that the oldest is more important and the younger needs to come first to prepare the way.

They also believe that the secondborn was higher/deeper in the womb and, therefore, must have been there longer. 

Telling Twins Who Is Older

Every parent has to decide whether it’s a good idea to tell their twins who was born first.

Ultimately, I think it depends on the personality of your twins and should be considered on an individual basis. 

If you know your twins have personalities that will cause them to seriously bicker over who is older or if you can foresee your older twin using it as leverage, it may be best to keep it a secret. 

However, in most situations, it is harmless to tell your twins who is older. They may not even care!

My husband and his twin sister learned at a young age who was born first.

My husband has never felt inferior to his twin sister because she is a few minutes older than him. In fact, they only think about it when they are asked. 

If you do choose to tell your children who is the oldest, make sure you don’t overemphasize the significance.

Knowing who is older shouldn’t make your twins feel like one is better and one is second best.

Birth Order in Twins

There is a lot of focus on birth order with most siblings, so how does this affect twins?

There’s quite a bit to know when it comes to their unique circumstances. Some of the information may be surprising.

What Determines Twin Birth Order

Twin birth order is usually determined by placement in the womb.

The twin lowest in the uterus is closest to the exit if a vaginal delivery occurs. This twin would be the oldest because he would come out first. 

In the case of a C-section, doctors try to grab the baby who has been labeled baby A during the pregnancy.

However, that’s not always what happens.

During a C-section, it may be necessary to take the baby who is having health issues before their sibling regardless of position.

Baby twin boys smiling while lying on their tummies.

How Birth Order Can Affect Twins

Birth order was a big deal in biblical times when it came to inheritance and birthright. Nowadays, it isn’t as important in that sense.

However, I do think we unintentionally create roles for our children based on birth order.  

In many families, the environment created by the parents impacts the children’s perspective of their role in the family, which is commonly based on birth order. 

It is typical for parents to give the oldest child more expectations and responsibilities simply because they are older than the other children in the family. 

Twins, however, are usually seen and treated as equals when it comes to their roles because they are the same age. 

On the other hand, if the parents rotate evenly through their children when it comes to responsibilities and privileges, I do not think birth order will really have too much of an effect on a child. 

With that said, there could be natural tendencies that develop due to the overall birth order in the family.

Twins born to a family that already has older kids will likely take on some of the typical youngest-child qualities.

Twins who are the oldest in the family may assume more control over their younger siblings.

Birth Order Affecting Personality and Qualities

For twins, it’s unlikely that birth order will affect their personalities or qualities such as strength and intelligence. 

Even for non-twin siblings, questions are being asked about how much impact birth order really has on personality and individual characteristics.

Many recent studies are finding that it isn’t as major of a factor as once believed.

Fraternal Twins Conception Timeline

For the most part, fraternal twins are conceived at the same time. Two eggs are released, and they are fertilized by sperm close to the same time.

However, since fraternal twins come from two separate eggs, this isn’t always the case.

With fraternal twins, either two eggs are released at the same time or one egg is released and then another follows later.

In the latter case, those eggs can be fertilized weeks apart.

Twins With Different Gestational Ages

Though it’s extremely rare, superfetation can cause fraternal twins to have different gestational ages.

This rare phenomenon can occur when one egg is fertilized and then another egg is released in the same cycle and fertilized.

The first egg will already be embedded in the uterine wall before the second egg, and this means twins can be days or even weeks apart in gestational age.

Longest Time Between Twins Birth

While very rare, it is possible for twins to have different birthdays.

This could happen due to one twin being born late at night and the other being born after midnight the next morning. 

In other rare cases, the birthday difference may be extreme.

In these cases, one twin might be born prematurely and doctors try to stop labor so the other twin can stay in longer.

This could result in birthdays separated by days, weeks, or months. 

The longest time between twins being born has been recorded at 90 days. In 1996, Molly West was born on January 1st.

Molly was three months premature, and since that is not ideal, doctors tried to stop the contractions so her twin brother could stay in longer.

It worked, and her twin brother, Benjamin West, was not born until March 30th.