What feature of genetic information helps in identifying individuals?

The sequence of DNA nucleotides is unique to each individual, with the exception of identical twins. This sequence is what makes up a person's genetic code and contains the instructions for building and maintaining an organism. The variations in these sequences among individuals create distinct genetic profiles, which can be used in forensic science, paternity testing, and genetic research to identify individuals accurately.

In contrast, while the structure of proteins, the size of chromosomes, and the number of genes can provide information about species and certain genetic conditions, they are not as unique to individuals as the nucleotide sequence. The protein structure can be similar across many individuals of the same species, while the size of chromosomes and the number of genes tend to be species-specific and do not vary significantly among individuals. Thus, the sequence of DNA nucleotides serves as a powerful tool for individual identification due to its high level of specificity and variability.