DNA Paternity Testing

Over the years, DNA paternity testing has become a virtual godsend for fathers or potential fathers and a veritable curse for others. While once only in the mind of science fiction writers, we are now able to conclusively prove if a man is the father of a child.

Throughout history, in many cultures, a woman need only accuse a man to be the father of her child thereby forcing him to provide for that child unless it was quite obvious there was no possibility the man could be the father, either due to known sterility or if the child was born a different race.  However, more recently, the burden of proof has shifted to the mother and many men abandoned children that may have been theirs.

Earlier, less conclusive tests, were conducted using the blood types of the parents and that of the child.  If the father was Type B and the mother Type A, the only conclusive evidence that the child may not be his, would be if the child tested Type O, leaving a huge margin for interpretation or error.  On the other hand, DNA paternity testing is almost 100% conclusive in it's results.  Although it cannot tell the difference between two brothers' particular DNA, it can definitively show from which family the DNA originated. As long as the two possible parents are from different families, DNA paternity testing will work conclusively.

DNA paternity testing works by isolating the DNA of both parents and then comparing it with the child’s DNA. The comparison is similar to that of blood testing, but individual DNA is being examined, as opposed to broad blood types.

To isolate the DNA, a sample of saliva is swabbed from the mouth and the DNA extracted using a restriction enzyme that cuts the DNA into identical and easily manageable lengths. The cut DNA pieces are then sorted according to size by the use of a special gel.  The DNA is placed at one end of a slab of gelatin and is then drawn through the gel by an electric current.  The gel acts like a sieve, allowing small DNA fragments to move more rapidly than larger ones.  

The result is that after the gel has separated the DNA according to size, a blot is made to trap the DNA in their positions, with small DNA fragments near one end of the blot and large ones near the other end.  The blot is now treated with another piece of DNA called a probe that binds to the DNA on the blot. If the patterns are identical, the result is a conclusive match. The technician can then reveal his findings of his DNA paternity testing to the courts or law enforcement agencies that may require the evidence to prosecute a deadbeat dad or allow a misnamed man to go free.