In child custody cases, when parentage is being disputed, courts will often require a DNA test to establish paternity. Once paternity has been established, judges can make decisions regarding child custody, visitation rights and enforce child support payments as well.
In every state across the nation, including here in Texas, DNA tests are considered absolute -- infallible. Usually if the test results say that you are not the parent, you are not given parental rights and are not obligated to pay child support. But what if you know you are the parent, had even given birth to the child, but are still told via DNA testing that you are not the child's biological parent?
It's something that has been toyed around with on shows such as CSI and House: people who have two distinct sets of DNA within their body. But while it may seem like fantasy, there is actually a real-life genetic disorder that causes this to happen, which could create legal problems in child custody cases.
The condition is called chimerism and it is considered incredibly rare with only about 30 cases having been documented worldwide. Scientists believe that people develop chimerism while still in the womb, when two fertilized eggs, each with distinct strands of genetic information, come together to form one organism.
Depending on the concentration of each genetic code within the body, a person with chimerism may have different genetic markers in one part of their body versus another part. It's only after testing different areas of the body that the two genetic codes are revealed.
Let's apply this now to custody cases.
If say a cheek swab taken from a "chimera" contains one set of genetic code and this was not the same code given to the child during pregnancy, a DNA test may not show a match between parent and child. Believing that the test is foolproof, a judge may assume that a person is not the biological parent when in fact they are. The judge could take away a person's parental rights or even remove the child from the home.
And as you can imagine, this could prove problematic, especially in cases where a person knows they are the parent despite glaring evidence that says they are not.
Sources: ABC News, "She's Her Own Twin," Aug. 15, 2006
Wisegeek.com, "What is Chimerism?"