How do you know? Genetics and molecular mechanisms may be the key to morality. Microdynamic development in the unborn child are incredibly important and can define whether someone is homosexual or hetrosexual, personality traits good and bad. That's why women should stay away from alcohol, drugs and noxious chemicals while pregnant. The beginning is crucial, if there is any damage done it affects the entire life of the individual mentally and physically.
I am not trying to justify human behaviour, but people aren't perfect so Allah forgives them.