In the event of siblings needing confirmation of their biological relationship, researching your family history will only tell you so much. In the absence of the biological parents for testing, the only definitive way to prove a biological relationship is through a DNA sibling test.

In the event of siblings needing confirmation of their biological relationship, researching your family history will only tell you so much. In the absence of the biological parents for testing, the only definitive way to prove a biological relationship is through a DNA sibling test.
The most common use for this test is to determine the likelihood of individuals having the same parents in common. In situations where one or both parents are unavailable or unwilling to be tested, the next option is to analyse DNA and make direct comparisons. The genetic laws of inheritance are made up in such a way that there can be big differences in sibling genetic profiles. Whilst it is possible to share many genes in common it is also possible to have inherited different genes from each parent, which would explain situations where the DNA results show a lack of genes in common.
Sibling testing can be used to determine the likelihood of two or more individuals being full siblings, half siblings or sharing no biological relationship meaning being not related. Full siblings by definition have two biological parents in common (the mother and father), whereas half siblings have only one parent in common (either the mother or the father). It is impossible to determine which parent they share without further DNA samples.
Determining Biological Relationships
By examining the number of shared genetic markers between individuals tested, the test can determine the probability of a biological relationship existing between the people. The aim of the DNA test is to analyse the amount of shared DNA and, by using scientific statistical analysis, to deduce any possible biological relationship. The stronger the commonality of the DNA shared means the greater the probability of a biological relationship existing.
It is strongly recommended when undergoing sibling analysis, especially a half sibling test, to include any parent (normally the mother) as this will help improve in the comparison and interpretation of the results. However, as it is common for parents 