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:

whether the child has been brought up and lives with the natural mother or the natural father

whether the childs mother is also seeking entry or whether she qualifies for admission

whether the father had exercised sole responsibility for the childs upbringing

whether the father had a previous undisclosed marriage or is in a polygamous marriage

Providing that the father is not in a polygamous marriage, has exercised the sole responsibility for the childs upbringing, and the childs mother is not seeking entry to the UK, the application is usually conceded by the Home Office.

When the child is related only to the mother, the situation is again different. This is a very delicate case and is usually handled with great sensitivity as the child may be illegitimate and the father may not be aware (even if he saw the DNA report). The impact of a disclosure of adultery could be disastrous for the woman. If the child has been brought up as child of the family he or she is usually admitted.

If DNA testing results indicate that the child is unrelated to the claimant, there may still be grounds for the Home Office to concede the application. If there is evidence that the child has been brought up as a member of the family he or she may be qualified for admission as de facto adopted child. In cases where the child is not a biological child of the parents but is related to them, the child may qualify as a dependant of a relative other than a parent.

DNA technology has significantly improved from the times when it was discovered, and now DNA testing has become a gold standard for cases where the relationship between people needs to be determined. Since 1985, thousands of children have been legally admitted to the UK and hundreds of families have been reunited. This can be largely attributed to Sir Alec Jeffreys discovery of DNA fingerprinting 20 years ago.