https://en.wikipedia.org/wiki/Maternal_effect https://en.wikipedia.org/wiki/Maternal_effect The egg contains mRNA or protein created by the mother that affects

https://en.wikipedia.org/wiki/Maternal_effect https://en.wikipedia.org/wiki/Maternal_effect The egg contains mRNA or protein created by the mother that affects the child's phentotype. It's unclear how much those non-genomic components affect organismal phenotypes; presumably, there is some minimal collection of factors that would suffice to allow us to construct an artificial egg cell that is viable for reproduction.