Glassberg's early years were devoted to nature; bird-watching, chasing butterflies,[3]: 23 and, with his younger brother, to chemistry experimentation.
Moving from the buildings of New York City to a place of forests and meadows on Long Island where his parents allowed him to roam stimulated his interest and love of nature which continues.
Jeffrey Glassberg met his future wife, Jane Scott, in a seminar course on bacteriophage lambda at Rice University.
Glassberg received his PhD in biology from Rice University in 1977, working on the genetics of bacteriophage SP01 DNA replication in the laboratory of Charlie Stewart.
[8][9][10] He then spent three years in the Biochemistry Department at the Stanford University School of Medicine where he was a post-doctoral fellow in Arthur Kornberg's laboratory doing research on DNA-binding proteins.
[11][12][13][14] Glassberg moved to Rockefeller University, New York City in 1979 and worked on creating a genetic system using the eukaryote, Crithidia fasciculata, a trypanosomatid parasite of mosquitos.
[15] Glassberg continued his scientific work as one of the founders of ACTAGEN (an acronym for advanced clinical testing and genetics) in March 1982.
[34] In 1999, Robert Robbins, then chair of the Department of Entomology at the Smithsonian Institution’s National Museum of Natural History, stated that "Glassberg’s butterfly guides have provided a new way for amateur naturalists to identify species without collecting them or dissecting them.