Statistical Calculations in Case of Brother-Sister Incest

Abstract

Incest is a sexual activity that happens between close family members that are not allowed to get married due to customs or law. In a case of incest between a brother and his married sister, a paternity test and a statistical analysis were performed at the laboratories of the Paternity and Kinship Division of the Medico-legal Directorate Baghdad, Iraq. Blood samples were taken from the concerned subjects in this case (newborn baby, mother, alleged father, and the husband) and placed on FTA cards. DNA extraction was done using Chelex®, then the amplification of extracted DNA was carried out using an AmpFlSTR® Identifiler kit. PCR products were run with a 3130xl Genetic Analyzer, and the data were analyzed with Gene-Mapper ID® Analysis Software V.3.2 software.The analysis of DNA profiles using 15 loci as well as the statistical analysis for calculating the paternity index confirmed the allegation of the brother-sister incest, since the baby inherited all the obligate alleles from the alleged father (suspected brother). With a 99.9998% probability of paternity, these results showed that even in the case of brother-sister incest, paternity could be proved using 15 DNA locus with a high rate of certainty.

Keywords

• forensic science
• paternity
• incest
• dna profile
• combined paternity index
• probability of paternity