Small differences make big consequences. That's the rule for DNA, where much as in computer code, tiny variations can radically change how huge chunks of the information apply.
Despite that our oversocialized media tells us that we're all genetically the same, or essentially the same, and thus that we shouldn't be disturbed at interbreeding or poor breeding. We're all equal, see.
But in humans, a difference of 1 in 1,000 (0.10%) amounts to approximately 3 million nucleotide differences, because the human genome has about 3 billion nucleotides. That's a huge amount of data in difference.
We also share 50% of our DNA with the lowly banana.
In addition, our DNA reveals our origins in fish and how we develop like them in the womb, thus even tiny (1 bit) variations in DNA can cause things to fail to happen, and the baby to develop incomplete.
Guess the story's more complex than mainstream media will tell us.