How Do Half Siblings Show Up On Ancestry DNA?

Taking an Ancestry DNA test can be a daunting but exciting experience. Your DNA contains the story of your family and so if you want to uncover more about your family it is an easy way to begin your journey. 

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However, you might be wondering how your relatives will show up on your DNA. Will they be clearly indicated, or will they simply be assigned by a number?

How will you be able to tell how someone is related to you? How will you be able to distinguish between your father’s side and your mother’s? How do half siblings show up on Ancestry DNA

These are all worthwhile questions and it is important to take the time to answer them. 

How do half siblings show up on Ancestry DNA

Learn more about your half siblings with an AncestryDNA test!

How Do My Relatives Show Up On Ancestry DNA? 

Your DNA relations will be divided into three categories – Close Family, Extended Family (4th – 6th cousins) and Extended Distant Family (6th – 8th cousins). 

Your Close Family will be made up of your closest genetic relatives such as your parents, your siblings and half siblings, your children, aunts and uncles and their children. The greater amount of centimorgans you share with the person the more likely you are to be closely related. 

A centimorgan is a unit of measuring linked DNA. If you share 3,443 centimorgans for example this means you share about half your DNA meaning the person is one of your parents.

The same process applies with other relations – the amount of centimorgans determines how closely related you are. 

Don’t worry about having to do a great amount of calculation to find out how someone is related to you. Ancestry provides the answer on each DNA test, using the amount of shared DNA to calculate your relationship. 

This means that if your half sibling appears on your Ancestry DNA test it will say that they are your half sibling or your 1st cousin. The reason for this is that half siblings and first cousins share similar amounts of DNA. 

How Do You Tell The Difference Between A Half Sibling And A First Cousin?

Given that Ancestry lists your half sibling as either being your half sibling or your first cousin, how are you supposed to determine which it is? 

Firstly, it’s worth checking that you know who the person is or not. If it’s a first cousin or half sibling that you already know about then it should simply be a matter of checking the name or username or contacting your relative to ask them if they have taken a DNA test. 

If you don’t know who the person is then it might be possible to figure out your relationship by checking to see if they have a family tree. Alongside its DNA service, Ancestry also provides family trees that can be linked to a person’s DNA results. 

If the family tree shows the relationship clearly then you will be able to tell from it whether the person is a half sibling or a first cousin. 

However, as is often the case with half siblings, there may be other factors involved which make determining your relationship more problematic. 

Learn more about your half siblings with an AncestryDNA test!

family photo of four half siblings

What If It Is A Half Sibling That You Don’t Know About? 

As is sometimes the case, people will take Ancestry DNA tests and discover that they have someone who could be a half sibling but who they don’t know about. 

This can be both distressing and confusing and there are certain ways that you can determine whether they are your half sibling or not. 

If there is no family tree, then check the amount of centimorgans that you share with them. The greater the amount, the more likely you are to share one parent with the other person. 

Once you have checked the amount of centimorgans it is worth looking at the ethnicity of the person. Alongside the DNA relatives that are produced by analyzing your DNA, Ancestry also produces a report on your ethnicity.

This will show which countries your ancestors came from and how much each ethnicity contributed to your DNA. 

For example, you might be 62% England and Northwestern Europe – if your half sibling shares a similar amount then this will help prove your relationship. Additionally, if you know the ethnicity of one or both of your parents then this can be useful in determining which parent you have in common. 

Learn more about your half siblings with an AncestryDNA test!

Should You Contact Your Half Sibling?

Once you have determined if this is your half sibling or not you must decide if you want to contact them or not. This can be a big step not just for you but for them also. 

Contacting a close relative, particularly one you may not know about, can be a daunting experience. There are a lot of emotions involved and as such, it would be wise to take time and think. 

The DNA test won’t be going anywhere so if you are unsure what to do then take time to consider whether you want to contact them. 

Of course, they may contact you first. You will then have to decide if you want to reply to them. This takes a great deal of thought given how it could potentially impact other people, including the half sibling. 

There is no right or wrong response and you should do whatever you think is best. 

Is Taking A Test Worth It? 

If you find a half sibling that you weren’t aware of, and this has an impact on you then you might wonder whether the test was worth taking or not.

Ancestry DNA tests are always worth taking regardless of the result because they provide information about yourself that you would otherwise not have known. 

Through your DNA you will be able to connect to your past in a way that was not possible thirty years ago. It is important to remember that whatever the result of the test that your 

DNA may be a part of you, but it does not define you. Only you can define yourself – your DNA will only help to fill in some blanks in your past. 

Learn more about your half siblings with an AncestryDNA test!


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