Expert: Ralph Salier - 7/11/2009

Question
in a paternity test of fetal tissue, is it possible to acquire a false positive if you test the potential father as a different race than they really are?

Answer
Hi Kayla,

In fetal tissue, in fact all tisssues, you will have one set of alleles from the mother and the other set from the father.  This is regardless of race and any thing else.  The mother's egg carries 1/2 of the genetic materials from the mother and the sperm from the father carries 1/2 of the genetic materials from the father.  When these combine to make a new fetus, the genetics are fixed.  If the fetus is male then it got the 1/2 of  the father's genetics with the "Y" chromosome and if it is female, then the "X" chromosome.  

Thus a paternity test always identifies the parents IF they have the genetic materials from both parents correct.