Chicken Eggs and DNA

[Joe_the_Lion]

In theory, could a scientist tell what farm egg (ie a household egg) came from which chicken?

A childish question I know, so I apologise.

[Clanad]

Not necessarily childish, Joe, but interesting when one stops to think it through. All the varieties of domestic chickens (Gallus gallus) in existence today, were created by altering the DNA of already existing chickens, usually by interbreeding for desired results. This means that any egg contains the DNA of it's mother if unfertilized, or the combination of DNA of both mother and father if fertilized. Theoretically (as your question inimates) the link could be made between any egg and it's progenitor(s)...
One factor making the process theoretically difficult is that most large flocks of laying hens (and turkeys) are very closely related, having been bred from nearly the same breeding pair to begin with. This is the reason those raising such flocks fear a large infection of a virus that could almost wipe out the entire related flocks (such as Bird Flu) since they are all so genetically similar...