Of course !
-- Child born when parents are 18.
Child is 36 when parents are 54.
-- Child born when the parents are 21.
Child is 42 when parents are 63.
-- Child born when parents are 24.
Child is 48 when parents are 72.
-- Child born when parents are 27.
Child is 54 when parents are 81.
-- Child born when parents are 30.
Child is 60 when parents are 90.
Stretching it:
-- Child born when parents are 33.
Child is 66 when parents are 99.
