How intelligent children will be depends on their parents...

Inside "Freaknonomics" by Steven D. Levitt and Stephen J. Dubner, a study was done to examine the effects of parents' actions on their children's IQ.

Sad to say, children's IQ is dependent mostly on parents' IQ as IQ is strongly hereditary... So even though parents may spend time with their children reading, their children may not be as intelligent unless they already are to begin with. Mothers can spend time with the child during the beginning years (0 - 3 years of age) but no statistically significant result was found to affect the child's IQ.

However, nothing is impossible. Research done by economist Bruce Sacerdote's paper titled, "The Nature and Nurture of Economic Outcomes," children* with weaker intelligence can be influenced by parents and obtain a comparable if not better future than other highly intelligent children. Do keep in mind that the parents do need a place education as an important role in the children's lives.

*Note: "In Sacerdote's paper, 3 adoption studies were used. Adoptive parents were found to cleverer, better educated, and better paid than the baby's biological parents. Although the children's grades were not good when they were young, upon they reaching adulthood the children were more likely to have better futures than similar children not put up for adoption." Quoted from Levitt and Dubner.