Definition
NUMGEN describes the number of generations in a given family unit. (See the documentation for FAMUNIT).
For example, a family unit comprised of parents and children has a NUMGEN of 2. A family unit which has co-resident grandparents, parents and children has a NUMGEN of 3. A family unit with only grandparents and grandchildren has a NUMGEN of 2, as the intervening generation is not resident.