Why is incest a sin and illegal when according to the Bible it is how the world began? God only made Adam and Eve so the Trillions of us started from there right?

Try looking at it this way ..... Adam and Eve were the first. Perhaps GOD, in His infinite wisdom, created other men and women, as is is certainly suggested.
GOD would not do anything contrary to His established order. He could as easily have created men and women in any number of places.

The fable is being taken far too literally.
Adam and Eve represented an upgrade step in evolution from the type of hominid that had prevailed up till then; and entire tribe of people, if you like, that had evolved to a newer level of brain function and ability.
With that came more responsibility, as portrayed in the forbidden fruit incident.

all the incest /marrying in family ,stopped with the Laws/Civilizing with Moses....and the Israelites.....God gave Laws prohibiting thus...to bring down descendants in yrs. before was necessary til Moses and teh Chosen people.....Abraham's descendants began with Isaac......
Its all in HIS Plan.....
the Laws also have MORAL standards for incest and pediphelia....incest of ones "child" is harming them mentally ,phsically and emotionally....and u will pay for harming a child......as for an adult child and mother or father...the genetic gene pool evolved to the point that this also will cause grave harm to a child if conceived...
u see ,alot of the uncivilized were TAMED by poor Moses and God....they were a stiff necked , uncivilized peoples, and most definitely proned to idol worship!!!! Moses did a long ,hard, arduos, Leadership for God and for the Israelites....those civilizing laws contained lots :like how to treat disease, get mold out of their homes, plagues, be good man and woman, husband and wife, take care of family, take care of GOD.....it stopped with Moses......was no longer necessary.....it had to begin in Genesis to "go forth and multiply" ;)justme

Because the progeny of close relations have a greater frequency of malformations.

Cuz its nasty.

Nowhere in the Bible does it state that Adam and Eve were the only people God created. It doesn't even say they were the first people created, though that is implied.

Incest is illegal as a result of the general disgust most people feel about the subject as a result of the westermarck effect, which evolved slowly as those less inclined to incest produced healthier offspring than those more inclined to incest. As birth control has become more effective and the rights of two consenting adults to do as they please in their own bedroom has been firmly established, there's really no reason other than general revulsion to keep incest illegal.

As for why it's a sin, I'm not even sure it is. Guess it depends on what, if any, god you believe in.

There are many cases of incest in the Bible, as well and the mythologies of many religions and cultures. The story of Noah, for example. Bear in mind though that there's no universally accepted definition of incest. To some people's cousin marriage is allowed and even preferred. To others, people related only through distant marriage generations back in their family tree are considered related and forbidden to marry.

Neat point,
if God made Eve out of Adam's rib,
(just wait till Christians claim this as
'scientific evidence of stem-cell research')
...Adam and Eve must be father & daughter.
*
Bible-authors have a fetish for incest between older men and teenage girls:
e.g., Lot's 2 daughters plying him with wine and sleeping with him in turns purely to get pregnant [Genesis:19: 31-38]
*
Tamar seducing Judah, her lecherous father-in-law, using a veil (!), which was the uniform of prostitutes in those days. [Genesis:38: 13-19]

http://www.population.govt.nz/myth-busters/MoreAliveThanLived.htm

Fewer than 130 billion modern humans have lived on the earth. That is a far cry from the trillions mentioned in the question.

Secondly, not every sin is illegal, nor every illegality a sin. The corollary is that not everything which is legal also is not a sin.

Incest was necessary in the beginning, but we now have easy access to people who are not our near relatives.

It's not a sin.

Look at Lot.

Does that mean you think incest is a good thing?

Actually good also made Lilith. Not that that makes a big difference to diversification...

I'm not sure of an answer, but you make a great point.

from an ethical standpoint, sex is ok if both parties give informed, un-coerced consent. in the case of the relationship between an adult and child or doctor and patient or even president and intern, we cannot be sure that the party with lesser power is not being coerced in subtle ways and in the case of children especially, whether they can truly be informed about what they agree to. even though it is conceivable that such a situation might arise where nobody suffers, experience shows reality to be quite different in at least close to all cases. society crafts rules based on this apparently true generalisation. relying on a collection of often confused writings by people from a far less civilised society as a moral compass is bound to cause confusion and difficulties and obviously does. if the bible is your guide, then slavery is fine but eating shellfish is an abomination and sinful.

worse than that . adam and eve only had 3 kids ...ALL BOYS ! ..

life's a mother f@#ker . ;-)

i have thought the same exact thing.

Man made incest illegal. God only had issue with one occasion in the Bible with incest. This is when Amron raped his sister Tamar. There would have been no problem IF afterwards Amron married his sister.

The Song of Solomon has much about incest and sex of all kinds. God has no problem with either.

Abraham and Sarah were half brother and sister, and Jacob married his two first cousin sisters and these and others are in the line of Jesus.

The prohibition in Leviticus was not to stop incest but to not have continous generations which can cause problems. Completely unrelated couples have children with birth defects at the rate of about 1.5%; first generation incest couples have problems at about 3%. This increases with each direct generation of offspring so by the third generation it is over 10% and should not be done. If the first generation offspring marries an unrelated person the rate again drops to 1.5%.

There are also some cases where incest can be useful as well as it can remove some problems in the DNA chain. When the incest child them marries outside the family this abnormality does not show up in the offspring.

Incest was deemed bad because of the church deeming it was bad by misusing the Old Testament Levitical laws and to declair it a sin to make money for the church to collect for absolution. Many of the laws written in the USA are based upon church law. Consentual incest should not be illegal.

Because only rednecks, brainwashed retards, really old people, halfwitted cretins and people without any logic still believe in god and the bible. This is the 21st century.

In the beginning it was not a sin. But later in Moses time God gave the laws against incest in Levidicous.
I do not believe Adam and Eve were the only people created.