As well as DNA testing, I research the family of everyone that tests starting from scratch. Here is the male line ancestry of George Rex who died 3 Apr 1839 in Knysna, South Africa that I have researched.
George Rex born 29 Aug 1765 baptised 2 Sep 1765 Whitechapel St Mary, London died 3 Apr 1839 Knysna, South Africa
John Rex (mother Theodora Hopkins) baptised 25 May 1726 Whitechapel St Mary, London married Sarah Creasey 17 Nov 1764 Whitechapel St Mary, London died 1792
Thomas Rix aka Thomas Rex baptised 24 Jan 1686 Whitechapel St Mary, London married (1) Margaret Constable 7 Apr 1706 St Katherine Creechurch, London married (2) Theodora Hopkins 31 Mar 1720 St Nicholas Cole Abbey, London buried 22 Nov 1736 Whitechapel St Mary, London
William Rix married Elizabeth
I have the baptism, marriage and burial images of the sources for these events if anyone would like copies.
Regarding the fable of descent from King George III, I would recommend http://en.wikipedia.org/wiki/George_Rexhttp://en.wikipedia.org/wiki/George_Rex which mentions the book "George Rex: Death of a Legend" which disproves the theory.
The Y-DNA test is scientific proof that there is no descent from George III. The descent is from Rix in Norfolk, England.
Please ask if you would like more information. If any male Rix or Ricks or Rex would like to test their Y-DNA let me know and I will explain what happens and advise what to do.