DNA testing involves collecting cell samples from both the baby and the father and comparing them in a laboratory to see if they match.
How is DNA collected?
Cells in tissues and body fluids contain DNA. Does urine contain DNA? Yes, but in smaller amounts than saliva or blood, it’s not worth the cost of a DNA test because it breaks down more quickly. In addition to sanitary concerns, urine samples are not used for DNA testing for these reasons.
Typically, the inside of the mouth is swabbed to collect saliva and cheek cells, which are often shed. Cheek swabbing is easy and painless. The person being tested can swab their own cheek, and parents can swab the cheek of an infant or young child. DNA testing using blood is also possible but done less frequently.
How the test works in the lab.
DNA has to be extracted and amplified for the sample to be viable. A geneticist calculates the probability that the man is the father of the test child based on an analysis of the data. Data are collected using short tandem repeat analysis to obtain information on at least 16 and up to 20 genetic markers. The test is very accurate. A positive result can mean that the man is the father in up to 99.9% of cases. 
Legal vs Illegal Paternity Testing?
Legal paternity testing is court-ordered to resolve a family law question, usually related to child support or custody. The findings constitute legal documents and are admissible in court.
However, sometimes you are willing to absorb the cost of a DNA test for your own peace of mind, not because a court in Sugar Land, TX is forcing you to. For this, you can use illegal DNA tests. It uses a less formal method and, although accurate, the results are not admissible in court.
Is prenatal testing possible?
In the past, prenatal DNA testing required taking fetal DNA samples from the womb. Because it carried the risk of miscarriage, it was performed only when necessary. However, non-invasive prenatal testing is possible, meaning you don’t have to wait until the baby is born to determine if you are the father.
What is tested with non-invasive prenatal paternity testing?
For prenatal testing, the father usually swabs the cheek to provide a sample of his DNA, just as he does after the baby is born. It is impossible to swab the mouth of an unborn baby, so the baby’s sample is collected by identifying free-floating fetal DNA in the mother’s blood sample. This can be done when the mother is at least seven weeks pregnant.
When will you get the DNA test results?
With the fastest DNA tests, results are usually available in three to five business days.
