To begin with, I just love how "Christians" become the generally accepted "crazy, nut job, religious lunatics." Soon enough Christians will be treated no different from Muslims because of small groups of radical sects who hold the same "core beliefs" but stray from the core truths. Fear of all-religion will soon become one of the greatest fear-mongering tools used to impose even more control over our freedoms - Just look at China and the USSR.
Half cocked research... Abraham was 600? When he got his sister pregnant? Genesis 20?
The facts: Abraham was 99 when Sarah conceived - 100 when she gave birth. The account is in Genesis 21 - and yes, it's considered a miracle. Sarah was Abraham's half-sister and his wife. However this account is of something that happened close to 4000 years ago. Marriages of that nature were common and not looked on as wrong. The gene pool was comparatively pure. They are forbidden in the Law 400 years later when Israel is sojourning in the dessert after leaving Egypt.
Lot did not "force himself" on his daughters. They made him drunk and slept with him, and he was unaware of it. This account is in Genesis 19.