• Are We Siblings?
• Basis of Sibship Analysis
• Collection of Fingerprick Blood Samples
• Initiating a Test
• Reports

Are We Siblings?

DNA analysis is often requested by people who want to know whether or not they are siblings (ie. brothers and sisters).  Sometimes these people were adopted and are trying to find their natural family, sometimes they discover one of their parents may have had other children and they are looking for other full or half-siblings.

Ideally, testing should be performed on samples from the potential siblings and their parents to determine whether each potential sibling could be a child of the same parents.  However, if the parents are not available, testing of the potential siblings only can also be informative (Note: if a person is under 18 years of age consent must be given by their legal guardian for a sample to be collected for DNA testing).

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When comparing the DNA of two people we look for DNA types that are common to both of them.  We can then determine statistically the chance that they would share that DNA if they are siblings, compared to if they are unrelated.  Two figures can be calculated:  the relative chance that they are full siblings and the relative chance that they are half siblings (1).  It is not possible to say with 100% certainty whether or not two people are definitely siblings.  The figures presented are an indication only.

Sibling analysis is only advisable if both parents are unavailable for testing.  The analysis is considerably more accurate and informative if you are able to test the parents involved.   If only one parent is available, this will still add information to the analysis. 

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Blood samples are collected by a simple fingerprick method.  This can either be performed by our staff at the VIFM in Southbank, Melbourne, or kits can be sent to the clients for blood collection at a convenient location.

Our fingerprick method involves piercing the tip of a finger with a single-use disposable device, as used daily by many diabetics.  A couple of drops of blood are soaked onto a piece of cloth (approximately 1cm x 1cm).  A portion of this blood stain is used in the DNA analysis.

If at any stage, you are planning to use the DNA testing results for any official/court purpose, the samples must be collected according to the Family Law Act requirements, involving sample collection by a medical professional and the provision of passport-sized photographs at the time of the appointment.    Any samples that have to be taken a second time in order to comply with the Family Law Act regulations will be charged accordingly.

If samples are collected outside of the VIFM, the samples must be transported to our laboratory for analysis.  This is usually arranged by our staff for a small cost (prices are available on request).  Note that biological specimens, including blood stains, cannot legally be mailed via Australia Post.

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To proceed with sibship analysis contact the VIFM to obtain an application form (or dowload it now Application for DNA Sibship Analysis).  This should be completed and returned to the VIFM with full payment (please contact us for current prices).  Once these are received each person involved will be contacted to make arrangements for blood collection.

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Reports of sibship analysis are usually issued within 5 working days after all samples are received.

1.    Wenk, R.E., M. Traver & F.A. Chiafari. (1996)  Determination of sibship in any two persons.  Transfusion.  36(3):259-262.