Why sibling testing is used
When the alleged parent cannot be tested, comparing siblings can help establish whether they share one parent, both parents, or neither.
Full versus half siblings
Full siblings share both biological parents and therefore far more markers than half siblings, who share one. The test produces a likelihood ratio comparing these possibilities.
Results are probabilistic
Sibling testing does not give the near-certainty of a direct parent-child test. Some cases return a strong indication; others are inconclusive because the marker overlap falls in an ambiguous range.
Improving confidence
Including a known biological parent of either sibling — usually the mother — substantially strengthens the analysis.
Discuss your family structure with us before ordering so the most informative design is chosen.