system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What happens to an unborn baby that is going to have a nut allergy (or any other type of allergy) when the mother consumes nuts?

Or are allergies only formed after birth? Is there any kind of genetic disposition to them, or anything like that? Does it hurt the child or is there no way for an unborn fetus to have allergies?

Thanks!
gpt
It doesn't hurt the child because the mother is processing the food for the child.  You mostly want to avoid things that get into the blood or can be passed through the placenta to the baby and have a harmful impact (such as alcohol).  Studies have actually shown that mothers who eat nuts during pregnancy have children who are less likely to be allergic to nuts.