Compare and contrast the terms Paternity Index (PI) and Combined Paternity Index (CPI). How does each contribute to paternity determination?

Key Concepts

Paternity Index (PI)

The Paternity Index (PI) is a statistical measure used in paternity testing that compares the likelihood of a genetic profile being present in a child if the alleged father is the biological parent versus if he is not. A PI greater than 1 indicates that the evidence supports the alleged father being the biological parent, while a PI less than 1 suggests the opposite. It is calculated for each genetic marker tested.

Combined Paternity Index (CPI)

The Combined Paternity Index (CPI) is an extension of the Paternity Index that integrates the PIs from multiple genetic markers to provide a more comprehensive assessment of paternity. The CPI is calculated by multiplying the PIs of all the markers tested, resulting in a single value that reflects the overall strength of the evidence. A higher CPI indicates a stronger likelihood of paternity.

Paternity Determination

Paternity determination involves using genetic testing to establish whether a man is the biological father of a child. This process typically relies on analyzing specific genetic markers, such as short tandem repeats (STRs), to compare the DNA of the child, the alleged father, and sometimes the mother. The results, expressed through PI and CPI, help quantify the probability of paternity, aiding legal and personal decisions.