Why is Sibling DNA testing less accurate than Paternity/Maternity Testing?
In a Paternity/Maternity test, exactly half of the child’s DNA will match the biological father and the other half will exactly match the biological mother. However, Siblings do not have the exact same DNA, as the inheritance of alleles from biological parents is random. At each genetic location (part of the DNA) a person possesses two alleles. A person will only pass one of these alleles to their offspring. Which allele is completely random. Therefore one child could inherit one allele from his father, while the child’s brother or sister could inherit the other. The allele inherited from the father joins with the allele inherited from the mother for that genetic location, when an egg is fertilized by a sperm. This is duplicated millions of times along the DNA molecule to form a child’s own unique DNA, made from half its fathers and half its mothers DNA. The calculation of the Sibling indexes allows for these differences and can therefore still provide accurate and useful results. It w
