FAQ: mtDNA
What is mtDNA testing?
Mitochondrial DNA (mtDNA) testing can be useful in cases of suspected full siblings. A negative mtDNA test will tell you that two individuals do not share the same maternal line, and would tell parents that their children are not full siblings. It will not tell you if the individuals are half siblings, because the children may share the same biological father.
mtDNA is passed from the mother to her offspring. It changes (mutates) very slowly over many generations, so if two individuals receive a “positive” mtDNA result, they share the same maternal line. This might be the biological mother, grandmother, or other ancestor. The children could be full siblings, cousins, or distant relatives. In the case of children from the same birth area with close birthdates and similar appearance, the parents might make an assumption that a positive mtDNA test indicates the children are twins. With children of different ages with similar looks and area of origin, parents might make an assumption that the children are full siblings.
A positive mtDNA test will not tell you that two children are definitely full siblings, just that they do share the same maternal line. The more conclusive answer comes from a negative mtDNA test, which will tell you that the children do not share the same maternal line and cannot be full siblings.
Should we consider mtDNA testing?
Yes, in most cases if:
1. Your DNA siblingship test gave you a negative or inconclusive full sibling result and you believe the children are full siblings or twins.
2. You did Twin Zygosity testing, with no proof that the children were twins. This testing is only for individuals KNOWN to be twins before testing. A “non identical” result in these cases produces a fraternal twin result when the individuals may not be related at all.
3. Your DNA siblingship test indicates a greater probability of half siblings but you feel the children are full siblings or twins.
Is mtDNA testing expensive?
Lab fees vary, but prices are coming down. mtDNA testing is generally a little more expensive than standard Siblingship DNA testing but it can give you more answers.
Additional FAQ’s