moms age at time of census
moms age when she first gave birth
1=white, 2=black, 3=other race
moms years of education
=1 if mom currently married
# of kids ever born to mom
=1 if 1st kid a boy
=1 if first birth is a twin
weeks worked in 1979
moms labor income, 1979
= 1 if the Mom worked at all in the previous year