evidence: Genetic testing helps verify a genetic – but not gestational – relationship in the absence of sufficient evidence to establish such a relationship. Relationships that may be used to establish paternity or maternity in citizenship claims arising from birth abroad to a U.S. citizen father or mother include: father-child, mother-child, child and full brother or sister, child and half brother or sister, and relationships between a child and a paternal aunt, uncle, or grandparent. [...] DNA paternity and maternity (father-child/mother-child) testing reliability has advanced to the industry-accepted standard of 99.99 percent. The accuracy of a DNA test conducted with a cheek swab is equivalent to a test conducted using a blood test. Consular officers may only accept test results reporting a 99.99 percent or greater degree of certainty with respect to paternity/maternity as sufficient to support a genetic relationship between a parent and child in passport and CRBA cases. When testing more distant relatives, a lower degree of probability of relationship to a U.S. citizen parent may be achieved, but it must also meet the requisite evidentiary standard in order to establish the claimed relationship to a U.S. citizen parent.