We are probably fourth cousins more or less. It gets confusing after a several generations, but we're cousins for sure.
Our common ancestors are Preston Allen and Lucy Boyd. According to Preston's second marriage his parents are William and Rachel Allen of Franklin County, Virginia, so far no luck finding any more information concerning Rachel. William Allen supposedly had brothers James, Stephen and Thomas.
William Allen received 88 acres from the Commonwealth of Virginia by virtue of Land Office Treasury Warrant #17,654, the warrant was issued July 5, 1783 and the land was surveyed in November 1792. This land was located in Patrick County on the North Waters of Paul's Creek. I haven't been able to locate Paul's Creek. The name may have changed or I need better maps. William was probably born about 1765, no idea where.
It will be hard finding George Martin's parents in the 1840 census because they only named the head of the house, everyone else is listed by sex and age. The best you will be able to do is pick out the Martins that have a son in the right age group. Just to make it more interesting, Lucy Boyd had a stepson named Linville Walker and he married Permilia Martin in Patrick County about 1850. They had at least 6 children. So it is possible that you are related to descendants of both of Lucy Boyd's husbands. You thought it was confusing before.