Scientists intend to track 100,000 children from the womb to age 21 to explore a number of different questions about early experiences' effect on later life. The National Children's Study, which Congress authorized in 2000, will be the largest of its kind, and researchers hope to find the causes and cures for various diseases and how much bad genes and environmental damage contribute to later poor health and misbehavior, as well as how conditions inside the womb affect children in the long term. Recent developments in computer technology, such as data mining, have made the elaborate project possible, as has the completion of the Human Genome Project. The study will consider, among other things, the effectiveness of vaccines in building immunity and the role of infection, before and after birth, in later hearing loss.