I'm pretty sure Clark had already met and had fallen for Lois by the time Kara's ship crash landed.

I need some hot cousins from the uk

Doing your first cousin is entirely legal in the UK.
"A big ball of wibbly wobbly, timey wimey stuff"
The Tenth Doctor explains all.

True.

i think op was referring more between superman and supergirl.
I used to be indecisive. Now, I'm not so sure.

Who said that they are related? They are from two different planets. They don't even share the same set of powers.

If Krypton truly mastered genetics then they don't need to fornicate. Instead of risking genetic defects they could make a completely artificial genome.

The flaws from incest are nullified by the advanced genetics of Kryptonians.
They're a thousand years at a minimum more advance than we humans.
Genetics is but one thing that they have mastered.
Hence why even in the comics, Superman wasn't completely against banging Kara, he just couldn't because it was illegal on Krypton.
No, really, that's a slightly smaller explanation of something from the comics.
But the idea that the genetic traits on Nietzsche's Ubermench would be that flawed is a bit nil. Yes, Superman was invented to embody the Nietzschean ideal.
I am a man with Asperger's Syndrome, so please forgive me if my posting seems weird.

https://en.wikipedia.org/wiki/Minimum_viable_population
The amount of incest required to grow a population from just two closely related people (or Kryptonians) would easily lead to high levels of undesirable genes.

This version of supergirl, too flat chested, no butt, too skinny and super annoying. Nope.
The version in the cartoons or smallville supergirl. I wouldn't even think twice. Infact, I would have started as soon as I said Hi
Are you an SJW ? If so, please kill yourself immediately! Thanks

Agreed, if the future of the species depended on it. People originally lived in very small groups, only recently people started to travel, you can still find villages where everybody is related to everybody