Afertilized ovum contains the code that will direct the unique development of the newly-formed person’s life.

genetic                            

Explanation:    

An ovum is a female matured reproductive cell which after the fertilization by a male sperm or cell will give produce an embryo inside the female. The fertilized egg or ovum contains certain genetic code which forms the basis of development of a newly formed life. A genetic code is important as it contains the basic building blocks of any individuals.

Hence the answer is -- genetic.

because the early people found out about it.

answer; ( dementia );