DNA Technical Lead, Cellmark Forensic Services, Forensic Reporting Team, Abingdon Laboratory, United Kingdom.
California Department of Justice, Redding, CA, USA.
Forensic Sci Int Genet. 2021 Mar;51:102434. doi: 10.1016/j.fsigen.2020.102434. Epub 2020 Dec 4.
DNA mixtures will have multiple donors under both the prosecution and alternate propositions when assigning a likelihood ratio for forensic DNA evidence. These donors are usually assumed to be unrelated to each other. In this paper, we make a small, preliminary examination of the potential effect of relaxing this assumption. We consider the simple situation of a two-person mixture with no dropout and a two-person major/minor mixture with dropout of the minor contributor. We make no adjustment for subpopulation effects. Mixtures were simulated under two assumptions: 1. that the donors were siblings 2. or that they were unrelated. Both unresolvable and major/minor mixtures were considered. We compared the likelihood ratio assuming sibship with the likelihood ratio assuming no relatedness. The LR for hypotheses assuming no relatedness is less than the LR assuming relatedness approximately 95% of the time when relatives are present in the mixture.
在为法医 DNA 证据分配似然比时，DNA 混合物在检方和替代命题下都将有多个供体。这些供体通常被假定彼此无关。在本文中，我们对放松此假设的潜在影响进行了初步的小范围研究。我们考虑了没有缺失的两人混合物和有缺失的两人主要/次要混合物的简单情况，次要供体的缺失。我们没有对亚群效应进行调整。在两种假设下对混合物进行了模拟：1. 供体是兄弟姐妹 2. 或者他们没有关系。同时考虑了无法解决的混合物和主要/次要混合物。我们比较了假设无亲缘关系的似然比与假设无亲缘关系的似然比。当混合物中存在亲属时，假设无亲缘关系的假设的似然比大约 95%的时间小于假设亲缘关系的似然比。
