Family ties that bind are especially true among America's grandparents and their grandchildren. Today, an increasing number of grandmas and grandpas are assuming the responsibility of taking care of their grandkids. The number of children under age 18 living in grandparent-maintained households increased from 2.2 million in 1970 to 2.3 million in 1980, to 3.9 million in 1997, according to a report by the U.S. Census Bureau. Moreover, a grandparent heads the household in 3 out of 4 families that have both grandparents and grandchildren living together. Some contributing factors to the increase in grandchildren in these "skipped generation" homes include teen pregnancy, divorce, the growth in drug use among parents, and the rapid rise of single-parent households.