Harry's lineage and its importance

[jferer]

No: HPFGUIDX 42099

Flower Fairy:"Lily had dark red hair. Just because Dumble & Lily have 
the same colour hair doesn't really mean that they are related. Harry 
& Cho have the same colour hair but they are not related.
I really hope Harry & the Weasleys (great name for a band) are not 
related because that would be too bad. How would Harry & Ginny ever 
fall in love? :)"

This is one of the problems the wizard world has. If there are as few 
wizards as there would have to be if there's only 300 students at 
Hogwarts, for example, then the gene pool is really, really small, 
even with marrying Muggles. In other words, most wizards *are* related 
somehow. It's the six degrees of separation thing, though in the 
wizard world it's probably more like three or even two. (after all, in 
the Muggle world, Jimmy Carter and Ronald Reagan are sixth cousins.)

The "Heir of Gryffindor" theory has the same problem. If descendancy 
is like what us Muggles are used to, then there ought to be Heirs of 
Slytherin and Heirs of Gryffindor and Heirs of Ravenclaw, etc., all 
over the place.