I know of some children who haven't had the physical characteristics, but as they have grown have had some learning or developmental delays, and FAS has been considered as a strong liklihood. I also taught one child who had some of the physical features, some behaviour issues (though nothing too full on) but no developmental delays and in fact was very clever.
As to how much alcohol, that is the magic question really - some cultures it is normal to have a drink a day even in pregnancy and there is no higher incidence of FAS at that level. Some people you hear of having a lot to drink trhough pregnancy and the child has been developmentally and intellectually normal.
Then there are cases wheere a child has had early detectable FAS signs and the mother has stated minimal drinks, often in the period before detecting pregnancy.

Such a hard one really.
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