Is Harry Potter related to Tom Riddle?

[Haggridd]

No: HPFGUIDX 24452

In this long hiatus between GoF and OoP, my mind wanders and wonders 
about whether Riddle and Harry are related by blood.  I do not mean 
the blood of the Resurrection Spell, but in the usual sense.  JKR 
makes it a point to have both Tom And Harry have the same black hair, 
which IIRC doesn't belong to anybody else described in detail.  She 
also has Tom state in great detail the similarities between himself 
and HP. One whopping flapping great RED Flag IMHO.  The questions 
remain, if there is a blood relationship, where does it lie, and have 
we been provided with enough information yet to deduce that 
relationship?  Tom is older than Harry' parents.  That is clear from 
internal evidence.  Wait a minute!  I just had a thought:  Does the 
wizarding world at large now know that Lord Voldemort was Tom Riddle? 
They did not as of CoS, and there are no references in subsequent 
books to imply it one way or the other.  Yes Dumbledore knows, but 
who else does?  So there are no instances where anybody could say, 
"Oy! That Tom Riddle is your uncle, Harry! How does it feel to be 
related to You-Know-Who?"  Anyway, I'm stumped.  Can anybody help me?

Haggridd