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DNA Q&A: Interpreting Your Results

DNA Q&A: Interpreting Your Results Due   to   the   science   behind   DNA   testing,   results   for   a   relationship   test   have   to   be   worded   in   a certain   way   that   isn’t   always   easily   understandable.   Here   are   the   interpretations   of   common statements in a report and what they mean for the results of your test. PATERNITY AND MATERNITY Paternity   and   maternity   testing   will   typically   return   one   of   two   results:   “cannot   be   excluded”   or “excluded”. If   your   report   contains   the   statement,   “…[name]   cannot   be   excluded    as   the   biological   mother   / father    of    [name]” ,    this    means    the    genetic    evidence    indicates    that    the    tested    parent    is    the biological parent of the tested child. If   your   report   contains   the   statement,   “[name]   is   excluded    as   the   biological   mother   /   father   of [name]” ,   this   means   that   there   is   no   direct   parent-to-child   biological   relationship   between   the tested parent and tested child. FIRST DEGREE: FULL SIBLINGS Full   siblingship   is   a   first   order   relationship   similar   to   paternity   and   maternity   but,   due   to   the decreased   likelihood   of   the   participants   sharing   an   allele   (25%   chance   for   full   siblings   vs   a   50% chance   for   parentage),   the   results   for   full   sibling   testing   are   not   as   straightforward   as   paternity   or maternity   tests.   There   are   several   results   you   could   receive   from   a   full   siblingship   test.   Please   look at the list below for the statement in your report to determine your results: “…the relationship is highly likely…” This   result   occurs   when   the   Calculated   Relationship   Index   (CRI)   is   greater   than   50.0.   The statement    means    the    genetic    evidence    significantly    favors    the    probability    that    the    tested participants are full siblings. “…the relationship is likely…” This   result   occurs   when   the   CRI   is   between   20.0   and   50.0.   The   statement   means   that   the   genetic evidence favors the probability that the tested participants are full siblings. “…the results support the relationship…” This   result   occurs   when   the   CRI   is   between   10.0   and   20.0.   The   statement   means   that   the   genetic evidence   indicates   that   the   tested   participants   may   be   full   siblings,   but   further   testing   with   a parent is strongly suggested. “…it is uncertain that [name] and [name] are related as first degree relatives.” This   result   occurs   when   the   CRI   is   between   0.1   and   10.0.   This   is   called   the   “grey   area”   where analysts   are   unable   to   say   one   way   or   the   other   whether   or   not   the   tested   participants   could  

be full siblings. Further testing with a parent is strongly suggested. “…it is unlikely that [name] and [name] are related as first degree relatives.” This   result   occurs   when   the   CRI   is   less   than   0.1.   The   statement   means   there   is   little   to   no   genetic evidence that the tested participants are full siblings. SECOND DEGREE: HALF SIBLINGS, UNCLE- OR AUNT-TO-CHILD, and GRANDPATERNITY Half   siblingship,   avuncular   (uncle-   or   aunt-to-child),   and   grandpaternity   testing   are   not   direct relationships   like   that   of   a   parent   to   a   child   or   potential   full   siblings.   Due   to   the   degree   of separation   in   the   relationship,   it   is   strongly   recommended   to   include   a   parent   that   is   directly related   to   one   or   both   participants.   There   are   several   results   you   could   receive   from   a   second degree    relationship    test.    Please    look    at    the    list    below    for    the    statement    in    your    report    to determine your results: “…the relationship is highly likely…” This   result   occurs   when   the   CRI   is   greater   than   100.0.   The   statement   means   the   genetic   evidence significantly   favors   the   probability   that   the   participants   share   the   biological   relationship   that   was tested. “…the relationship is likely…” This   result   occurs   when   the   CRI   is   between   50.0   and   100.0.   The   statement   means   that   the genetic   evidence   favors   the   probability   that   the   participants   share   the   biological   relationship   that was tested. “…the results support the relationship…” This   result   occurs   when   the   CRI   is   between   20.0   and   50.0.   The   statement   means   that   the   genetic evidence   indicates   that   the   participants   may   share   the   biological   relationship   that   was   tested,   but certain   alleles   in   the   tested   DNA   are   very   common   in   the   population   and   therefore   give   less weight   to   the   alleged   relationship.   It   is   strongly   recommended   to   include   a   parent   that   is   directly related to one or both participants to improve the clarity of this result. “…it is uncertain that [name] and [name] are related as second degree relatives.” This   result   occurs   when   the   CRI   is   between   less   than   20.0.   This   is   called   the   “grey   area”   where analysts   are   unable   to   say   one   way   or   the   other   whether   or   not   the   participants   share   the biological   relationship   that   was   tested.   Further   testing   with   a   parent   that   is   directly   related   to   one or   both   participants   is   strongly   suggested.   The   lower   the   CRI   value,   the   less   likely   that   tested participants share the biological relationship that was tested. Y-STR MALE LINEAGE Y-STR testing between two males will return one of two results: “consistent” or “not consistent”. If   your   report   contains   the   statement   “The   DNA   profile   produced   from   the   sample   labeled   as [name]   is   consistent    with   the   profile   produced   from   the   sample   labeled   as   [name]” ,   this   means that   the   tested   participants   are   likely   to   have   come   from   the   same   male   lineage.   If   testing   two brothers, this can indicate that they share the same father. If   your   report   contains   the   statement   “The   DNA   profile   produced   from   the   sample   labeled   as [name]   is   not   consistent    with   the   profile   produced   from   the   sample   labeled   as   [name]” ,   this means that the two participants did not come from the same male lineage. If your results were not listed here, please contact us to discuss your results.