It would be interesting to know the parents IQ but does seem to conform to other evidence that low-income children, at least in the US, have fewer opportunities for their genetic potential to flourish. If I recall correctly the heritability of intelligence among poor children has been put somewhere around 25% vs 60-70 from wealthy families. For poor children in the South Korea as well (?), the family environment seems to matter quite a bit.
IQ isn't always intrinsically linked to parental IQ. Some brilliant, high IQ children are born to parents of average IQ. The reverse also occurs. Each child needs to be evaluated to really know what potential is present. Maximize the potential present. Don't try to make a silk purse of a sow's ear nor toss a diamond into a bucket of tar.