help with the JAPAN DNA project from ftdna

hi, i have decided to join the japan dna project as i want to confirm the family stories of japanese heritage from my nan, but im still a bit confused as to whether the project will actually help out, i could just take a normal test that reveals my full heritage but at this moment in time i just want a test that can confirm japanese heritage or not, does anybody know anything about genetics and what this projects capabilities are?

It depends what sort of test. Y-DNA is useless for you - it only traces the paternal line. mtDNA (mitochondrial) goes through the maternal line - tracing your mum's mum's mum's mum's... (etc). atDNA (autosomal) uses a set of markers spread throughout the genes.

The main problem is the way it's marketed and the idea that you can tell if you are X% of some nationality. The "ethnicity" tests using atDNA work by looking for groups of people who share common genetic features. At that level you can't distinguish between Japanese, Korean, etc.

I would be extremely wary of anybody who tells you they can test for Japanese heritage - especially if that's "can, if you pay us lots of money".