"Most groups look more homogeneous from the outside than the inside."

But that doesn't mean that they really are all that different in the end. It reminds me a of joke as told by Emo Philips that I think is quite apropos:

==-==-=

A man was walking across a bridge when he saw someone about to jump. He ran over and said, "Don't do it! There's so much to live for!"

"Like what?" the person asked.

"Well, are you religious?"

"Yes."

"Me too! Are you Christian or Jewish?"

"Christian."

"Me too! Protestant or Catholic?"

"Protestant."

"Me too! What denomination?"

"Baptist."

"Me too! Northern Baptist or Southern Baptist?"

"Northern Baptist."

"Me too! Northern Baptist Conservative or Northern Baptist Liberal?"

"Northern Baptist Conservative."

"Me too! Northern Baptist Conservative Covenant or Northern Baptist Conservative Council?"

"Northern Baptist Conservative Council."

"Me too! Northern Baptist Conservative Council of 1879, or Northern Baptist Conservative Council of 1912?"

"Northern Baptist Conservative Council of 1912."

The man stepped back, eyes narrowing, and yelled, "Die, heretic scum!" and pushed the other off the bridge.