Well, we know this stretch of genetic code certainly isn't a retrovirus
because it is not found in the appropriate density gradients after being
centrifuged.

And we know it isn't a  sexually transmissible agent because of the
extremely low transmission rates of discordant couples.

That means it is most likely a product of our own cells.

The overwhelming number of people that show prescence of this stretch of
genetic code referred to as "HIV" are certainly influenced by lifestyle
factors such as drug use, pollutants, or nutritional deficiencies.

Read on-

Lifestyle may alter gene activity
Researchers find DNA becomes less alike as twins age
By RICK WEISS
Washington Post

WASHINGTON - A mysterious biological mechanism that subtly changes the
way people's genes behave may account for many of the surprising
differences between identical twins, researchers announced.

Geneticists said the new work, by a team of scientists who studied the
DNA of more than 80 twins, strengthens the case that a fledgling
research field called epigenetics holds the long-sought answer to one of
biology's toughest questions: How do environmental influences, such as
exposure to pollutants, consumption of certain foods or powerful
emotional experiences, produce lasting and potentially life-altering
changes in a person's DNA?

Epigenetics could explain many of the twists of fate that affect
ordinary people ? why one person may be struck by cancer, for example,
while another is spared, even though neither's DNA harbors a
cancer-causing mutation.

"This is how the environment talks to the genome," said Rudolf Jaenisch,
a geneticist at the Whitehead Institute for Biomedical Research in
Cambridge, Mass., who was not part of the project. "This paper says
lifestyle, or environmental influences or whatever you want to call
them, have a real influence on your DNA."

Stephen Baylin, a professor of oncology and medicine at Johns Hopkins
Medical Institutions in Baltimore, said the new work points to the roots
of a host of chronic diseases. "This could lead to far-reaching
revelations about how our environment breeds predispositions for lots of
diseases, like diabetes, cancer and heart disease."

Human cells have tens of thousands of genes in them, each with its own
job, such as producing energy. But only certain genes are active at any
given time or in any cell type while the rest are appropriately dormant
? a grand orchestration that adds up to a smooth-running life.

The new research, led by Mario Fraga and Manel Esteller of the Spanish
National Cancer Center in Madrid, focused on two biological mechanisms
that influence gene activity. In one, called DNA methylation, enzymes
inside a cell attach a minuscule molecular decoration to a gene,
deactivating that gene. In the other, called histone acetylation, a
dormant gene is made active again.

These altered genetic settings can last a lifetime and can be important
if, say, the gene turned off is one that protects against cancer.

In the new work, described in the current issue of Proceedings of the
National Academy of Sciences, researchers measured the extent to which
twins of various ages, from 3 to 74, differed in the number and variety
of genes that had been either turned on or shut down by epigenetic
processes. They found young twins had almost identical epigenetic
profiles but that with age their profiles became more and more
divergent.

In a finding that scientists said was particularly groundbreaking, the
epigenetic profiles of twins who had been raised apart or had especially
different life experiences ? including nutritional habits, history of
illness, physical activity, and use of tobacco, alcohol and drugs ?
differed more than those who had lived together longer or shared similar
environments and experiences.

Small epigenetic events before birth probably account for many of the
minor distinguishing differences in the appearance, personality and
general health of young twins, Esteller said, and a lifetime of further
epigenetic changes gradually increases individuality.

" We know that to err is human, but the HIV/AIDS hypothesis is one hell
of a mistake"
Dr. Kary Mullis, Nobel Laureate and inventor of Polymerase Chain
Reaction.