Scientific Basis of STR Parentage Testing
According to Mendel's laws of inheritance, each parent passes on half of their DNA to their child. As a result, the child carries half of the father's DNA and half of the mother's DNA, and it is impossible for the child to carry DNA that neither parent possesses. By using a 16-locus fluorescent reagent kit to test samples rich in nuclear DNA, if all loci conform to this rule, it indicates a biological parent-child relationship. If two or more loci do not conform to this rule, it excludes a biological parent-child relationship (in cases of gene mutation, a maternal sample may be required or additional loci tested).
What is Mitochondrial DNA Testing (Maternal Inheritance)?
Mitochondrial DNA follows the characteristic of maternal inheritance during genetic transmission. That is, mitochondrial DNA is passed from the mother to both sons and daughters, and daughters can further pass their own mitochondrial DNA to their offspring. It can be used to identify individuals from the same maternal lineage.
What is Y-Chromosome STR Testing (Paternal Inheritance)?
The Y chromosome is a male-specific chromosome, and its inheritance follows the characteristic of paternal inheritance. This means that the father passes his Y chromosome to his son but not to his daughter, and the Y chromosome profiles of the father and son are completely identical. All male descendants from the same grandfather will have consistent Y-STR profiles. It can be used to identify grandfather-grandson and uncle-nephew relationships, as well as family lineage and surname identification.