Well, to be sure, heredity exists, but it is only a secondary phenomenon. This question can never be answered by science as it is now. Theosophy gives some general clues when we combine the seven jewels together. At this point I should point out that there are many questions of details which require a life-long study and research. At the end of this document I will provide some keys to be used in this kind of research.
Heredity confines itself to the physical aspect of man.
The fifth jewel of wisdom concerns the principle of progressive evolution . Now, evolution as it is understood by Darwin and his followers concerns itself with the transformation of forms and the survival of the fittest. Theosophy regards these processes as secondary processes and states clearly that consciousness is the primary factor in evolution. No phenomenon is possible without an active, intelligent force. Each phenomenon is evolved from Universal Life-Matter in a long line of differentiations.