Mothers who worry their role is over when they push their adolescent kids out of the nest have another worry coming, says a UC Davis human development researcher. "The parent-child relationships can go on for 70 years, now that many people's parents are still alive when the adult children are in their 60s," says Carolyn Aldwin, professor of human development at UC Davis. The fact that life expectancy for Americans is now 76, compared to 46 100 years ago has many implications, she says. "There are many autonomy issues, which can be very interesting when parents in their 60s and 70s are helping their children financially." Often this assistance involves major expenditures, such as down payments for houses or grandchildren's college education. This type of support is not usually a problem, since for most families, the gifts represent part of mutual reciprocity that occurs in families, Aldwin says. But sometimes, adult children in their 40s have not become financially independent, which can be an issue. The lengthening of life spans also means that many more multigenerational families exist than in previous centuries. That issue of autonomy often must be renegotiated, this time for the aging parent. "The tricky part comes when parents become very old and frail," Aldwin says. "Many elders resist when their children try to take control, or they may request more help than an adult child can provide." Aldwin has spent the last 20 years studying transitions to adulthood, midlife adulthood development and aging.