What hormones? What are you even talking about?fectin wrote:Okay. So what determines mom's hormone concentrations? What determines baby's sensitivity to that hormone?
I think your response is pretty good evidence for my original statement.
Mom's "hormone concentrations" (estrogens, progestins, and testosterone) are determined by her genetics. "How do I respond to pregnancy" is coded in a mother's DNA. Under normal circumstances the human endocrine system maintains an appropriate balance of systemic hormones for fetal development.
Likewise, a developing fetus is just running the program imprinted in its DNA. Cells multiply and differentiate based on those instructions and the availability of resources (amino acids, fats, etc). The mother's hormone levels during pregnancy are maintained so that the uterus stays in proper condition to support a developing fetus. Details like the genetic sex of the fetus are determined at the time of conception and don't change unless the DNA mutates. Maternal hormone levels don't wildly fluctuate and cause the whole project to change course unless you introduce exogenous sources of estrogen/testosterone/progesterone.
If an environmental factor causes a mutation, the DNA of the fetus has changed. Therefore, the change is genetic. If DNA isn't changed, the change isn't genetic.
Magery in Shadowrun not being inherited by identical twins or clones or whatever despite being linked to "the Magus gene" is clearly a result of some Sixth World ambient mana fuckery. You have to have the gene to be a mage. Environmental conditions have to trigger it for it to activate and do anything. The fact that you can't just clone mages and then expose them to the appropriate environmental trigger can only be explained so many ways, but the one that is ultimately going to get applied is "it's magic, so sometimes people with the Magus gene are mages and sometimes they aren't."