"IQ scores obtained when 8,170 boys and girls were 10 years old and their alcohol intake and any problems when they were 30 years old." [I'm assuming not many

"IQ scores obtained when 8,170 boys and girls were 10 years old and their alcohol intake and any problems when they were 30 years old." [I'm assuming not many of them were heavy drinkers in kindergarten. Go on, call me naive]