One of my sisters just had her fourth kid and she has done a heck of a job they are all bright. Many times having more than two kids helps them to interact with outher people.
4. Limit your family to two children, especially if you have a lower income.
Nor do I. I was one of nine children, born to lower-middle class parents. I was accepted to join Mensa out of high school. I believe that the interaction with my siblings was a large part of my intellectual growth. Many children in abject poverty is probably not the best scenario, however.