Sibling DNA – recognizing unique bonds this National Siblings Day

National Siblings Day

Today (April 10) is National Siblings Day: a day designed to celebrate the special bonds shared by siblings across the country.

Organised by the Siblings Day Foundation, National Siblings Day honors the role that brothers and sisters play in our lives.

Much like on Mother’s Day and Father’s Day, families celebrating their siblings are encouraged to use this day as an opportunity to spend quality time together.

As a laboratory that offers sibling DNA testing, we know that the bonds between brothers and sisters go beyond the day-to-day and into our genetics.

In this blog, we examine sibling DNA, and how brothers and sisters share a unique bond at a genetic level.

How do siblings share DNA?

The feelings of closeness that many people share with their siblings can often be explained by their shared upbringing, but also by their shared DNA.

After all, biological siblings can sometimes have similar physical characteristics and even personality traits. In the case of identical twins, these similarities are often even more pronounced.

Every person inherits half of their genetic material from each of their parents, with related people sharing more DNA than people who are not related.

When both people have the same biological parents (mom and dad), they are classed as full siblings. Half-siblings are individuals who only share one biological parent – either mom or dad.

Full siblings on average share about 50% of their DNA, while half-siblings share about 25%.

What is a sibling DNA test used for?

In most instances, individuals will know if their brother or sister is their full or half-sibling, simply because they already know how many biological parents they share.

However, in some circumstances, such as where there is a question of paternity (who a child’s father is), it may be necessary to perform a sibling DNA test to determine the likelihood of two or more individuals being full siblings.

For a sibling DNA test – like the test we offer at AlphaBiolabs – cheek swabs are used to collect DNA samples from each sibling taking part in the test.

For the most conclusive result, we will also ask for the biological mother’s DNA sample, if available. However, this is not essential, and we can still perform a sibling DNA test without the mother’s sample.

Once these samples arrive at the laboratory, our in-house geneticists analyze and compare the DNA samples to determine the genetic profile of the possible siblings and calculate a sibling DNA index or likelihood ratio:

  • A likelihood of greater than 10 supports that the tested individuals are either full or half siblings
  • A likelihood of less than 0.1 is not supportive, meaning the individuals are unlikely to be related
  • A likelihood which falls between 0.1 and 10 is considered inconclusive, which means a relationship cannot be determined based on the statistical probability from the analysis

Where can I buy a Sibling DNA Test?

It’s easy to order a Sibling DNA Test online now, direct from our accredited laboratory.

Once you have placed your order, we will ship your test kit out to you immediately.

Your test kit will contain everything you need to collect your DNA samples and return them to our laboratory, using your preferred shipping method.

Once we receive your DNA samples, testing can begin. Your secure results will be emailed to you within 3 business days.*

Got questions about our DNA testing? Call 727 325 2902, email or visit our Learning Center.

*From receipt of your samples at our laboratory.

Sibling DNA Test

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