V71: Uses parents' birthyear at 0, 5, 15, +; disconfirms; supports
V72: Uses parents' birthyear at 0, 5, 15, +; supports

(The code was changed to V73 before I committed to git
V73: Uses parents' birthyear at 0, 5, 15, +; disconfirms
V74: Uses parents' birthyear at 0, 5, 15, +; disconfirms; unlikely
Reverting back to V73