Y-Chromosome Testing

  Y-Chromosome Test is used to provide additional evidence in difficult paternity cases in which the alleged father is not available for testing—indirectly, it can tell whether or not a child is related to the alleged father's brothers and other male relatives who share a common paternal line.

  The genealogy DNA test is based on the fact that the Y chromosome is passed from father to son relatively unchanged through many generations. The illustration to the right shows a typical inheritance pattern for the Y chromosome. Because the Y chromosome follows the same father-to-son pattern much like surnames in Western culture, the test has also been referred to as a "Surname Test."

Although the Y chromosome is only found in males, women can also indirectly participate in a Y-STR DNA test if they are interested in determining their paternal ancestry. They would need to ask a biological male relative, such as a father, brother, paternal uncle, or paternal grandfather to contribute a sample for comparison testing with her potential paternal relative or ancestor

In a Y-STR DNA test, specific locations on the Y chromosome are examined to generate a Y-STR profile for each male tested. Males who are related through their fathers will tend to have the same or similar Y-STR profiles, and males who are not related will likely have different Y-STR profiles.

Most genealogy DNA testing companies allow for you to enter your DNA profile into a database with the hope of finding matches or possible relatives. At our Laboratory, we provide the scientific confirmation of the relationship once you have identified a possible relative from your ancestry search—by performing a comparative analysis, testing both you and the possible relative using 17 Y-STR markers, which will tell you whether or not your Y-STR profiles are consistent, or not consistent, with the conclusion that you and the possible relative(s) may be related through a common male ancestor.

In a paternity situation where the alleged father is missing, Y-STR analysis cannot distinguish a specific relationship between males who belong to the same paternal line. However, it is useful for excluding males from an alleged biological relationship. For example, if a male child and his alleged uncle (alleged father’s full brother) are tested, their Y-STR profiles must match. If they do not, then the alleged uncle is excluded (not considered a biological uncle) and the alleged father is probably not the biological father.

Sample Collection

  Samples for a DNA test are routinely collected using the painless and simple buccal swab, similar to a cotton-tipped swab, but made of the special material Pur-Wraps®. The swab is rubbed against the inside cheek of the test participant, and loose cheek cells adhere to the swab. Unlike regular cotton swabs, Pur-Wraps® provides a consistent surface for sample collection and DNA extraction.

  Samples are collected using a chain of custody documentation process that ensures your results will be accepted by courts and other government agencies. Part of this process requires that a neutral third-party, such as a local laboratory or hospital, collect your samples. When you come to the sample collection appointment, you will be asked to do the following to meet the chain of custody requirements:

  • Present government-issued identification for the adults
  • Present one of the following for minors: birth certificate or social security card
  • Be photographed and fingerprinted
  • Complete a Client Identification and Consent Form (the minor’s consent form should be signed by the legal guardian)

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