Science has for some time considered the, genetic burden upon the human species considering that we have made laws and culture that to some extend prevents males competing in death battles for females, etc. Pretty much anybody gets to breed and yet the end result is that no genetic burden has been detected.
The human genome today would be far more robust than say, the age of Adam, when people married first cousins and lived in small groups in close proximity thus created a limited gene pool.
There is a huge variation amongst different groups but today the Japanese and Chinese peoples are becoming much taller simply because of increased quality food and nutrient. Humans belong in a single family group, there is no species. Humans are less genetically diverse than a single troupe of wild chimps.
The Bible is about reality. There is not a Bible reality and then a reality we live in. When it speaks of giants and global floods, first man, special creation, these are symbolic so as to define their spiritual connection as opposed to the every day events of life.
Whatever G.d is, it has bound us to natural order, the laws of maths and science, reality, common sense and reason. Anything that strays beyond these constraints is a product of human imagination.
