[ghostdiver]

DNA is your UUID/GUID

[rmc]

Presuming you're not a chimera http://en.wikipedia.org/wiki/Chimera_(genetics)

[pavel_lishin]

Unless you're one of a set of twins/triplets/etc.

[heynairb]

append datetime string of birth. Boom problem solved.

[rmccue]

What if the twins are delivered via Caesarean, with the exact same datetime recorded? Including datetime (even as a string) also includes the aforementioned falsehoods about time.

[tehwalrus]

unless you have a twin, or other tuplet siblings.

[ghostdiver]

or a clone:)

[ars_technician]

Unless you're a twin