Let kids denote the number of children over born to a woman, and let educ denote years

Question:

Let kids denote the number of children over born to a woman, and let educ denote years of education for the woman. A simple model relating fertility to years of education is
kids = (0 + (1 educ + u,
where u is the unobserved error.
(i) What kinds of factors are contained in u? Are these likely to be correlated with level of education?
(ii) Will a simple regression analysis uncover the ceteris paribus effect of education on fertility? Explain?