"Thus people learn their blood types before they marry"
should be
"Thus people aware of this problem learn their blood types before they deliberately attempt to conceive"
unless it was a statement designed to provoke exactly this analysis. ;)
"Thus people learn their blood types before they marry"
should be
"Thus people aware of this problem learn their blood types before they deliberately attempt to conceive"
unless it was a statement designed to provoke exactly this analysis. ;)