According to the Bible we are all descendants of Adam and Eve. How did racism devlope/begin since we are all kin?

This is an ironic question, as bigotry. slavery, misogyny, genocide and anti-intellectualism are all espoused by the Bible, itself a product of Bronze Age ignorance.
Ignorance seeds hate - the progenitor of racism and bigotry. 

Adam and Eve are fictional characters, and I could cite entire fields of science as evidence to that point. I won’t bore you further with that. The Bible is an exceedingly poor source of reliable historical facts. 

It is long past time we grow out of the spell of primitive, indefensible nonsense. 

This post was edited by Don Barzini at November 29, 2019 11:13 AM MST

I agree with Don's answer ... however, even if we all descended from two people, it wouldn't be uncommon for there to exist discrimination against each other.

How many families have discrimination against members less than 3 generations removed from each other?  Lots
Or a church that has a dispute, and splits into two congregations.

So ... a tribe of people gets in an argument, splitting the tribe to go separate ways.
TribeA is told that TribeB is a bunch of idiots, and vice-versa.
The children grow up never knowing anyone from the other tribe, but also "knowing" those people are idiots.

Another way is plain old "anybody different than me is not to be trusted" instinct.