Genealogy is the science of proving that you're not a bastard after all, whatever your colleagues may say about you - and what would Edgar know anyway? I mean, if anyone's the b-word, it's Edgar!
Uh, forget all that.
So you draw up this big chart, and it's got you as the end-product of countless generations, and you take all the rumours you've heard from your aged relatives about how you're the eighth generation descendant from the illegitimate older brother of George III, and you try to trace up from your parents to him, and you seek desperately for any evidence at all that this older brother ever even existed, and you weave a teetering edifice of lies, and hope Auntie Gwen was wrong about your mother cheating on your father, and then you have...
A family tree chart! And you hang it on your wall, and give copies to your relatives, and point smugly to the royal crest nine generations back without mentioning you don't have the right to use it for anything, and you hope oh so desperately that none of the relatives you gave copies to does anything silly with it, like make any attempt to check any of it.