Sure they do. you just have to trace the trail back far enough.

All that was needed for "life" to occur is that one very small group of chemicals that had combined be able to divide... and do it just once. (We define "life" as being able to reproduce, even if it is just at the cellular or molecular level. It doesn't have to be intelligent....)

Because if they did it just once, then the two that resulted would carry the DNA to do it again. And the chances of that happening were billions and billions and billions to one, and since there were nothing but billions and billions and billions of chemical compounds, it was an absolutely certainty that it would occur here on this planet----billions of years ago.

Time was not a factor--since the universe anywhere had nothing but time, and billions of planets where this could occur. It happened on this planet, it has, did, or will likely occur on others since the universe is loaded with planets with similar chemical arrangements as ours.

So, think big, and often.

As well, the DNA in a fly is exactly as yours, as is an oak tree, as in bacteria. You share common DNA with viruses. All the same stuff, just in different orders and amounts.

And all of the molecules that make you up--all--were used by some other living thing at one time or another. We have all been made of recycled molecules, and when we no longer use them they will be recycled to some other living thing sooner or later. You have DNA and molecules used by Beethoven, but none yet from Elvis. He hasn't been dead long enough.

Read The Ancestor's Tale, an extremely interesting work. It's 600 pages, so if you read poorly, or don't have at least a biology course in your education, don't bother, or wait. Read as well Cosmos by Carl Sagan.. both hugely interesting. Both on the NYTimes Best Seller list in Science . Sagan's book was made into a series, that likely you can buy on Discoverychannel.com. And the other book is available in paperback, it was so popular... Fascinating stuff.