I have often indicated that there is no contradiction between a scientific fact that is correctly presented and the facts brought forward by Spiritual Science. It is just as if someone were to say: Here is a man; how comes it that he is alive? It is because he has lungs inside him and there is air outside. Needless to say, that is quite correct.
But someone else may turn up and say: This man is alive for an entirely different reason. A fortnight ago he fell into the water and I jumped in after him and pulled him out; but for that he would not be alive today! Both these assertions are correct. In the same way, natural science is quite correct when it says that a man bears within himself characteristics inherited from his ancestors; but it is equally correct to attribute them to his karma and other factors.
Source: Rudolf Steiner – GA 141 – Between death and rebirth: Lecture Eight – Berlin, February 11, 1913