Practice question

Short Tandem Repeats exhibit polymorphism due to variation in number of tandemly repeated core units at a locus. DNA polymerase slippage adds or deletes repeat units during replication, generating alleles differing in length but not necessarily base composition, methylation state or expression level. Parentage testing exploits highly polymorphic allele length variation; child inherits one allele length from each parent. Base composition and epigenetic modifications do not determine STR genotype. Counting repeat number provides quantifiable allelic diversity crucial for forensic identity and kinship resolution.