DNA TEST

Using modern genetic Science, even a  saliva sample, can help predict a person's age Accurately .

With a process called methylation -- a chemical modification of one of the four building blocks that make up our DNA. Researchers scoured the men's genomes and identified 88 sites on the DNA that strongly correlated methylation to age.

Methylation's relationship with age is so strong that scientists can identify how old someone is by examining just two of the 3 billion building blocks that make up our genome.

Try googling for Methylation.