What test are you talking about that is non-invasive? Are you sure it is to determine paternity?
Yes it called the non invasive paternity test that they say is 100% accurate but I am a lil skeptical
This prenatal paternity test uses only the mother's blood - and samples from the alleged father(s) - to determine the paternity of the child as early as 13 weeks into the pregnancy. No blood is taken from the alleged father(s).
I don't understand how it works but that is the info I found on it.