Pregnancy sickness: What do you think? Does it make sense? Do you find the theory compelling?

What about women who don't experience much sickness? There are certainly individual differences in terms of how much sickness different pregnant women experience. How might the theory account for those differences?

And if pregnancy sickness is an adaptation to protect the fetus, why don't pregnant women find alcohol and cigarette smoke as repulsive as$,$ say, fried foods? Can the theory account for those details?