Some Thoughts On Noah And Lot

Similarities:

• Noah sees the destruction of the world, Lot sees destruction of Sdom.
• In the story of Noah the destruction is caused by water, in Lot by water.
• Both are told to close themselves from the world - Noah in an Ark, Lot in his house.
• In both cases the root ש.ח.ת is used: (Noah - Gen 6:13, Lot- Gen 19:13-14).
• In both cases G-d "Rains" his punishment (מטר):  Noah - Gen 7:4, Lot - Gen 19:24)
• After the destruction, both Noah and Lot drink  wine, and then are raped by a family member . In Noah's case A son (and another son saves him - see what I previously wrote about on this topic here), in Lot's case two daughters.

I'm not sure what to do with these similarities. The story of Sdom seems like a repeat of the story of the flood, though on a much smaller scale. The ending of both stories, family incest is where I'm really puzzled. Why does the destruction of the world, automatically lead to incest? Why does the torah need to retell the story twice? It is also noteworthy that Noah and Lot are the only two people to get drunk in the book of Genesis.