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April 01, 2018 Uniform Parentage Act

UPA 2017: The Science of It All

By: George C. Maha

In crafting the Uniform Parentage Act of 2017, the drafting committee faced the challenge of not only understanding the law—it also had to understand very complex scientific issues. These issues ranged from artificial reproduction to mitochondrial replacement therapy to genetic testing to determine parentage. One article, Article 5, Genetic Testing, provides a detailed legal and scientific framework for using genetic testing to solve disputed parentage.

Ethnic or Racial Designation

Article 5 starts with definitions.

Section 501(2). “Ethnic or racial group” means, for the purpose of genetic testing, a recognized group that an individual identifies as the individual’s ancestry or part of the ancestry or that is identified by other information.

Why ask questions about the ethnic or racial group? When a laboratory makes calculations of the weight of the genetic evidence, it bases those calculations on the tested person’s self-identified ethnic or racial groups, as those designations will generally provide the lowest probabilities. In a parentage case, this lower calculation biases the test in the direction of nonpaternity, which is helpful for those who are disputing paternity. Thus, individuals are asked to provide the ethnic or racial groups, as these provide a conservative measure of parentage.

Relationship  Index

Race is used in the calculation of a relationship index. For each genetic marker tested (markers are also called “loci”), a relationship index is calculated. A definition of the relationship index is provided in the UPA.

Section 501(5). “Relationship index” means a likelihood ratio that compares the probability of a genetic marker given a hypothesized genetic relationship and the probability of the genetic marker given a genetic relationship between the child and a random individual of the ethnic or racial group used in the hypothesized genetic relationship.

This index is a likelihood ratio. Depending on the situation, the likelihood ratio may be called, for example, a paternity index, maternity index, or avuncular index. Regardless of the situation, it is a ratio of two probabilities. For example, in a paternity case, it is a ratio of the probability of the alleged father producing the child given the results of the testing compared to the probability that a random, unrelated man of the same ethnic or racial group as the alleged father produced the child. Once a likelihood ratio is calculated for each genetic marker tested, the individual likelihood ratios are multiplied together to obtain a combined relationship index.

The UPA states that a combined relationship index of 100 indicates that a tested individual is the genetic parent of the child.

Section 506(a). Subject to a challenge under subsection (b), an individual is identified under this [act] as a genetic parent of a child if genetic testing complies with this [article] and the results of the testing disclose:
(1)  the individual has at least a 99 percent probability of parentage, using a prior probability of 0.50, as calculated by using the combined relationship index obtained in the testing; and
(2)  a combined relationship index of at least 100 to 1.

Probability of Parentage

The other major calculation present with relationship cases is the probability of parentage. This is a probability that the questioned parentage relationship is correct. The probability of parentage uses two factors in its calculation: the combined relationship index and prior probability. Prior probability offersa way to incorporate other evidence into the determination of the probability of parentage. This other evidence may include any relevant evidence, such as frequency of intercourse, birth control failure, and other factors. Typically these factors are the types of evidence that would be heard in court in the absence of genetic testing.

In fact, such evidence is a UPA prerequisite to obtaining an order for a genetic test, as an individual must provide, under oath, a statement alleging or denying the possibility of geneticparentage. Because the laboratory performing the testing is not involved with gathering this other evidence, laboratories typically use a frequency of 0.5 for the prior probability. See Brown v. Smith, 1526 S.E. 2d 686 (N.C. Ct. App. 2000). A prior probability of 0.5 means that the nongenetic evidence for or against parentage is weighted equally for the purpose of the laboratory's calculation. This 0.5 prior probability was incorporated into the UPA. If the use of the 0.5 is opposed, evidence of what is believed to be the correct prior probability should be presented to the trier of fact and given to the laboratory to recalculate the probability of parentage.


Article 5, Genetic Testing, provides a detailed legal and scientific framework for using genetic testing to solve disputed parentage.

A common misconception is that 0.5 means that the probability of parentage is starting a the probability of fifty percent. It is not. This is one factor in the calculation and, depending on the other factor, the combined relationship index, the probability of parentage can be less than fifty percent. With the large combined relationship indices seen in modern parentage testing, any reasonable change to the prior probability has little or no effect on the probability of parentage. A widely cited case that has a good discussion of this calculation is Griffith v. State, 976 S.W.2d 241 (Tex. Ct. App. 1998).

Frequency Tables

A scientifically interesting section of Article 5 provides rules for the use of frequency tables. As noted, the calculations used in genetic testing are based on the ethnic or racial group of the tested persons. Therefore, in order to make these calculations, laboratories must develop frequencies for the genetic markers used in their testing. Many laboratories will have frequency tables for the five major racial groups: African Americans, Asians, Caucasians, Hispanics, and Native Americans. Some laboratories will have frequencies for common populations they may test, such as, for example, Puerto Rican and Mexican populations, rather than general Hispanic populations. The UPA indicates that if an individual objects to the ethnic or racial group used in the initial calculations, a laboratory can recalculate using the desired frequencies, or the opposing individual can provide the needed calculations through his or her own expert.

One important point to understand is that changing the ethnic or racial groups will not change a result indicating that an alleged parent may, in fact, be the parent to a result that excludes that possibility. Changing the frequencies changes the combined relationship index; the likelihood ratio of the combined relationship index may increase, decrease, or remain about the same. In modern parentage testing with the newest testing kits, laboratories routinely report combined relationship indices in the billions. Thus changing the frequency tables has no effect on an outcome indicating that an individual is not excluded as a parent; the individual will remain identified as a parent under the UPA and is scientifically highly likely to be the parent. The use of a combined relationship index (also called a combined likelihood ratio) of 100 to 1 in the UPA follows the scientific standards in the relationship testing standards of AABB (formerly the American Association of Blood Banks), a nonprofit organization representing individuals and institutions involved in the fields of transfusion medicine and cellular therapies. AABB has been involved in writing relationship standards since the 1980s, as testing at that time was largely performed using the same testing used in transfusion medicine. AABB provides laboratory accreditation that meets the requirement of UPA section 504(a).

Challenging the Identification of an Individual as a Genetic Parent

As indicated above, UPA section 506(a) states that a combined relationship index of 100 indicates that a tested individual is the genetic parent of the child in question. Challenges to the testing results are addressed in the UPA by section 506(b).

Section 506(b). An individual identified under subsection (a) as a genetic parent of the child may challenge the genetic testing results only by other genetic testing satisfying the requirements of this [article] which:
(1)  excludes the individual as a genetic parent of the child; or
(2)  identifies another individual as a possible genetic parent of the child .…

Thus, an individual may challenge results indicating parentage only by obtaining another genetic test. For the challenge to be successful, the other test must exclude the individual as a possible genetic parent or identify another individual as a possible genetic parent.

Test results indicate the probability of parentage, and as a probability, there is always a small chance that some additional testing, not performed by the first laboratory, may exclude the tested individual. With modern testing, however, that probability is exceedingly small.

When  requesting  additional  testing  to  challenge a finding of  parentage,  it is important to specify which additional tests are to be performed. If the alleged parent is excluded by  the  first  test  as  a  possible  parent,  ordering the same test to confirm the testing is typically appropriate. But if the alleged parent is challenging a test that does not exclude him from possible parentage, repeating the same testing is unlikely to change the results. The appropriate approach in this situation is to order additional testing that is different from the testing originally performed, although some overlap may be  appropriate  to  confirm  that  the  same person was tested. While the testing is very powerful, it does not provide a yes/no answer. If the additional testing does exclude the tested individual as a possible parent, the results of the first test are not to be interpreted as laboratory error but, rather, as a reflection of the limitations of the testing. See, e.g., Cauthen v. Yates, 716 So. 2d 1256 (Ala. Civ. App. 1998).

An individual may challenge results indicating parentage only by obtaining another genetic test.

When obtaining another genetic test, it is important to keep in mind that the original test is evidence and, as with any evidence, there may be other problems that can be corrected by a new test. Current parentage testing is commonly performed using buccal swabs, and attempts to alter results are not unheard of. One unusual means of alteration has been one in which a participant puts someone else’s saliva in his mouth. This approach will probably be obvious to the testing laboratory;  it should result in the laboratory not issuing a  report and asking for new samples. See L.J. Martinez-Gonzalez, et al., Intentional Mixed Buccal Cell Reference Sample in a Paternity Case, 52 J. Forensic Sci. 397 (2007). Additional testing is also called for   in cases where an  alleged parent  sends  an  imposter  to  the  collection  procedure. As a laboratory will not know the participants, detection of the imposter will be dependent on the other parties to the testing recognizing from photographs typically taken as part of the chain of custody that the tested person was not the correct individual. See, e.g., State v. Brueggeman, 24 P.3d 583 (Alaska Ct. App. 2001).

Testing with a Missing Alleged Parent

Another section of UPA Article 5 provides a mechanism for determining parentage when an alleged parent is not available. The process can involve testing other biological relatives of the alleged parents. Many combinations can be used. The parents of the missing alleged parent, siblings, and aunts and uncles are all individuals who are commonly submitted for this type of testing. These individuals are used to provide information on the possible genetic markers in the missing parent.

The biological relatives ideal for testing are both of the missing alleged parent’s biological parents (the alleged grandparents), as they will contain all the biological material their child has. When both of the alleged grandparents are not available,  other relatives can be used. The greater the number of relatives tested, the more   likely an expert is to be able to reconstruct the genetic material in the missing parent. As there are many possible combinations of relatives to test, who to test is best discussed with the testing laboratory. For a discussion of testing when a parent is missing. See George C. Maha, Determining Paternity After Death: Genetic Testing When a Party is Not Available, in Disputed Paternity Proceedings (N. M. Vitek, ed., Mathhew Bender & Co.) (1999).


There is one relationship that the current genetic testing methods have not been able to differentiate, and that is when the alleged parent has an identical sibling who could also be the genetic parent. Identical siblings will have identical results. In a parentage setting, if an alleged parent has an identical twin, both will have the same combined relationship index. UPA section 511 addresses this situation.

Section 511. Identical Siblings.
(a)     If the court finds there is reason to believe that an alleged genetic parent has an identical sibling and evidence that the sibling may be a genetic parent of the child, the court may order genetic testing of the sibling.
(b)      If more than one sibling is identified under Section 506 as a genetic parent of the child, the court may rely on nongenetic evidence to adjudicate which sibling is a genetic parent of the child.

Thus, the UPA provides that a court will resolve this issue by evaluating nongenetic evidence. This follows the principle set out in Ill. Dept. of Public Aid v. Whitworth, 652 N.E.2d 458 (Ill. App. Ct. 1995), a paternity case with twin alleged fathers in which the trial court properly relied on the nongenetic evidence to conclude which of the twins was the father.

There is new technology that shows promise in distinguishing identical twins. In the near future, science may be able to regularly distinguish identical siblings, and, if and when that occurs, the alleged parentage relationship will be resolvable under other sections of the UPA. See Jacqueline Weber-Lehmann et al., Finding the Needle in the Haystack: Differentiating ‘‘Identical’’ Twins in Paternity Testing and Forensics by Ultra-Deep Next Generation Sequencing, 9 Forensic Sci Int’l: Genetics 42 (2014).

Assisted Reproduction

UPA Article 7, Assisted Reproduction, is concerned with the broad topic of parentage of children produced by assisted reproduction. It does not differentiate among any individual techniques of assisted reproduction other than surrogacy. Regardless    of the assisted reproduction method used, the parentage of the resulting child is determined under Article 7, except where a surrogacy agreement is involved, in which case Article 8 applies.

A key provision within Article 7 is section 703, which requires consent to assisted reproduction. The types of consent are found in section 704 and can be a signed record or consent shown by other evidence.

Section 703. Parentage of Child of Assisted Reproduction. An individual who consents under Section 704 to assisted reproduction by a woman with the intent to be a parent of a child conceived by the assisted reproduction is a parent of the child.

Assisted reproduction, per the UPA’s definitional sections, includes intrauterine or intracervical insemination, donation of gametes, donation of embryos, in vitro fertilization, and intracytoplasmic injections. The process of intrauterine insemination (IUI) is simply the injection of sperm directly into the uterus. The process involves washing the sperm before injection. IUI may be used, for example, where there are sperm mobility problems or cervical problems. In intracervical insemination (ICI), sperm are placed directly on the cervix. ICI is a method that may be used for home insemination.

In vitro fertilization is another form of assisted reproduction that results in what is commonly called a “test tube baby.” As the name implies, the ovum (egg) is fertilized by sperm outside the body of the mother. This technique is used to treat a variety of reproductive issues.


One form of assisted reproduction, surrogacy, is addressed in Article 8.

Either the ovum or sperm can be from a donor. Once fertilized, the resulting embryo is transferred back into the mother’s uterus. One step that may be a part of the in vitro fertilization process is intracytoplasmic sperm injections (ICSI) in which sperm are injected directly into the ovum. This method is commonly used to treat sperm mobility issues.

As mentioned, one form of assisted reproduction, surrogacy, is provided for in Article 8 of the UPA. Surrogacy is the practice by which a women agrees to become pregnant and deliver a child that she does not intend to parent. The surrogate, under the UPA, must become pregnant using assisted reproduction. There are two types of surrogates. A genetic surrogate is a woman who agrees to donate one of her eggs for assisted reproduction. This surrogate is a genetic parent but has agreed to relinquish the child to the intended parents. The second type of surrogate is the woman who is a gestational parent. The gestational surrogate is implanted with an embryo created by some means of assisted reproduction, but the surrogate has no genetic contribution to the resulting child.


An aspect of reproduction that is often overlooked is that there are actually three genetic entities involved in reproduction: the ovum (egg), sperm, and another genetic element called the mitochondrion (plural: mitochondria). The mitochondria are found outside the nucleus in the cytoplasm of the ovum and are maternally transmitted. They have their own DNA separate from the DNA found in the ovum nucleus or sperm. After fertilization, they are found in every cell. Mitochondria produce energy for the cell. Unfortunately, mitochondria can also be a source of genetic diseases in humans.

One area of promising medical research for treatment of mitochondrial genetic diseases has been based on the potential seen in donated normal mitochondria. The donation procedure was recently approved for use in the United Kingdom but is not approved for use in the United States. The U.S. Food and Drug Administration is reviewing recommendations from the U.S. National Academies of Sciences, Engineering, and Medicine. One question the National Academies have raised is the impact of having three parents: a mother, a father, and a mitochondria donor. If the FDA approves the use of this technique, the long-term impact on the child of having three parents will be monitored. It is important to keep in mind that, under the UPA, a donor is not a parent.


This brief article has attempted to highlight important aspects of the science of UPA 2017 and to explain their intersection with the law. The science is complex and can be daunting to practitioners of law. Still, much of the language in UPA 2017 is similar to that of UPA 2000 and UPA 2002. The science relied upon in the current version can be traced to requirements set out in paternity determinations required by welfare reform legislation known as the Personal Responsibility and Work Opportunity Act of 1996. The science of paternity testing goes back to the early 1900s, however, and has been constantly improving and is now extremely powerful compared to the older tests.

The requirement for accreditation for parentage testing laboratories in the Act provides a safeguard against the use of inappropriate science. Accreditation standards are written by experts in the field of parentage testing to protect the integrity of the scientific process. fa

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George C. Maha

George C. Maha ([email protected]), JD, PhD, is associate vice president and laboratory director of the  DNA  Identification  Testing  Division,  Laboratory  Corporation  of  America  Holdings.  He  was an observer to the ULC’s revision of the UPA 2000, 2002, and 2017, and was vice chair of the     Paternity Committee of the ABA’s Family Law Section. He is a Board-Certified Medical Geneticist, Medical Technologist, and Laboratory Director.