A child of European immigrants, Weg grew up in the Manhattan borough of New York City.
After enrolling in a biology master's program at New York University, Weg’s husband accepted a job in Los Angeles, where she then enrolled in the University of Southern California and earned a secondary teaching credential.
She then taught for two years but returned USC for a master's degree in biological sciences.
She was one of several professors who did the initial planning for the Leonard Davis School of Gerontology at the University of Southern California (which opened in 1975).
Weg specialties included sexuality in the later years, appropriate nutrition, and promoting positive images of aging.