I do doubt you, and the whole Adam and Eve thing.
Though I do think throughout history there’s been a lot of incest.
In the creation story in Genesis chapter 1, it says “God created man in his own image, in the image of God he created him, male and female he created them” (v. 27). It doesn’t say just one pair—there is no indication of numbers. Chapter 2 is very different with Adam being created first and Eve later after Adam is unable to find a suitable helpmate.
You might want to take a gander at what's called "Y-chromosome-Adam" and "X-chromosome-Eve". A decent write-up by an atheist is at https://scienceblogs.com/authority/2007/07/17/adam-eve-and-why-they-never-go. In it the author says, rightly so, not to make too much of the geneticists referring to everyone's common male ancestor as "Adam" and common female ancestor as "Eve" because they didn't do it to affirm belief in the Bible. The scientists named them that just to pick names for whoever the mysterious couple was in the past that they were trying to derive more info about by studying everybody's genes.
And what they concluded, as noted in the article, is that
Eve died more than 50,000 years before Adam was born
This, of course, is talking about the genetic researched "Eve" (based on variations in everyone's portion of DNA that comes from our mothers" and genetic researched "Adam", not the two people from the Bible. I've read others say it's closer to 100,000 years. And so, the author says that there couldn't have been a real Adam and Eve or they'd have to be in the same generation. It also stumped the researches because they assumed that everyone's common male ancestor would be in the same generation as everyone's common female ancestor --- including if we got here through natural selection. Thus, they figured their study was messed up and did it again years later, only to get the same result.
To which I, and others, say it confirms the Noah story of the flood later in Genesis. Of all the people listed in the Bible as being on the ark, all of the men are from the same family line: Noah and his sons. The women listed are their wives -- perhaps from multiple family lines. Thus Genesis says our common male ancestor doesn't have to go all the way back to Adam, but only to Noah. But our common female ancestor would have to go back further, to whoever the common female ancestor was of the ark wives. Perhaps all the way back to Eve.