DNA testing is routinely used in immigration cases to prove whether a child under 18 is a biological child of or, in some cases, is related to an individual with a leave to remain in the UK. Most DNA tests for immigration reasons are parentage testing (paternity or maternity) but in some cases a grand parentage or avuncular (whether a child is a nephew or a niece of the sponsor) test is employed to prove an alleged relationship.
When the child is outside the UK, a DNA test is normally arranged by an ECO. In such cases, DNA samples are taken from applicants at a post overseas and sent to a UK-based laboratory together with the samples of the sponsor, which in most cases is taken in the UK. If the child is already in the UK, DNA testing could be conducted in a Home Office-appointed laboratory or arranged privately or via solicitor. The DNA testing report provides an assessment as to the nature of relationship between the tested individuals and states the probability of this relationship.
According to the Home Office guidelines, in assessing DNA reports, the question to be addressed is whether the evidence establishes the relevant relationships on a balance of probability. If a DNA report concludes that the probability of a claimed relationship is at least three-times greater than any other relationship, it should normally be accepted as proof of that relationship without further enquiry. If the probability of the claimed relationship is only twice as likely (or less) than any other relationship, the case is usually reviewed as a whole. However, the Home Office admits that even a low balance of probability in favor of the claimed relationship is substantial evidence and should be accepted unless there is strong evidence to the contrary. If relationship was the sole ground on which the application was refused, and it was later established by means of DNA evidence, the Home Office usually concedes the case.
In cases where several children are to be tested, the fact that some children are related to the claimant does not constitute the evidence in favor of other children who were not tested. The application with regards to the latter will be refused on the ground that there is not enough evidence to support the alleged relationship unless DNA testing results prove otherwise.
When DNA testing proves the alleged relationship, the Home Office usually concedes the application; however, in some cases, the Home Office has specific guidelines as to their treatment. This applies to cases when the child is related to only one of the parents, or is not related to them at all.
The immigration law treats a case where a child is related only to one of the parents differently. Treatment will depend on whether the child is related to the mother or to the father.
When the child is revealed to be the biological child of the father but not the mother, the Home Office usually seeks an explanation from the family on the following issues: