For fetus growing in the womb, there are several influences that shape its future prakriti.
First, it is impact of शुक्र & शोणित (रज,वीर्य). Parental legacy. 7 layered generational legacy. शुक्रशोणित प्रकृति.
Second, it is timing of the conception and health of the womb that has impact on the growing fetus. For example, वर्षाषु मारुतो दुष्ट: | Conception during monsoon means influence of Vayu. कालगर्भाशय प्रकृति|
Third, it is mother’s food intake. Mental state. Activities.
Fourth, it is महाभूतविकार प्रकृति | Past life karma and past life interaction with panch-mahabhut.
Now, all these forces together shape you and me in womb.
Here, genes play mere 25% (or less) role ( शुक्रशोणित प्रकृति.)
This is the reason why GMO is highly inefficient and random technology. 75% control is with mother nature.(In fact, it is 100% mother’s rule 
🙂 ) Sometimes favorable results, sometimes not. IR8 rice (Famous green revolution hero, is now zero) to btCotton : shining examples of failures.
