DNA paternity testing is based off the fact that half of our DNA is inherited from our father and the other half from our mother. Laboratories determine parentage with samples collected from mother, child and alleged father.

The laboratory compares the mother and child\'s DNA to see what matches. The remaining DNA markers are compared to the alleged father\'s sample to see if they match. In a properly performed test, positive results are 99 percent or higher and negative results are always 0 percent.

The easiest and most common method of conducting a paternity test is with an oral (buccal) swab. You rub the swab on the inside of your mouth to collect saliva, which is then tested. When it is impossible to obtain a saliva sample, it is possible to send samples obtained through other methods.

Biological

* Hair: Hair must have the roots attached when used for paternity testing. The best way to acquire the hair is from a hairbrush, comb or clippings from an electric razor.

Get as many hairs as possible before having them tested. Make sure not to touch the roots when handling the hair, as this will contaminate the sample.

* Blood: You can get blood samples from a regular blood draw with a syringe. If this is not possible, obtain them from blood spots on paper, tissues, clothing and furniture. The amount of exposure the blood has had to contaminants such as human touch or cleaners will greatly affect the results.

* Nails: Nail clippings are the most used type of samples in cases where the alleged father is recently deceased. As with hair samples, handle the nail clippings as little as possible.

* Semen: It is possible to use both liquid and dry semen for paternity testing. Liquid should be absorbed into a clean Q-tip and air dried for an hour before being packaged up. When the semen is dried, send the soiled material directly to a lab or use the Q-tip method described above.

* Bones: Bone samples are not used very often for paternity testing because it is extremely difficult to acquire DNA from them. A qualified individual should collect these types of samples and only after calling the lab in advance.

* Earwax: It is possible to use earwax from a Q-tip for paternity testing. Do not touch the ends of the Q-tip.

* Amniotic Fluid or Placenta Cells: It is possible to perform paternity testing before the baby is even born. An OB-GYN will accomplish this by getting amniotic fluid from the sac surrounding the fetus.

Chorionic Villi Sampling, or CVS, is a test where cells are taken from the placenta. Both methods of obtaining samples are guided by an ultrasound to reduce the risk to mother and baby, and must be performed by an OB-GYN.

Common Items

* Cigarettes: As long as the cigarette butt is not contaminated, it is a wonderful DNA source. Never handle the cigarette from the butt end since you will be risking contamination. The best results are obtained from cigarettes that have not been shared.

* Toothbrush or Dental Floss: An uncontaminated toothbrush or strands of dental floss are good DNA sources for paternity testing. As with cigarette samples, unshared toothbrushes produce the best results.

Do not handle the brush end. If sending dental floss do not use your hands to pick it up. Completely air-dry the brush or floss before sending it off.

* Gum: Uncontaminated chewing gum is another type of sample that produces good paternity testing results. To avoid contamination do not use your hand when picking the gum up.

* Handkerchief or Kleenex: You can use nasal mucous deposited on used handkerchiefs or Kleenexes for paternity testing.