Whatever happened to the theory of biorhythms? I remember writing a program for my Sinclair ZX81 which graphed the three (?) aspects of it and indicated when they’d coincide highs, hoorah, and lows, booh.
I wonder how the aspects match up for two people. 
Think I might have an explore of this tomorrow on modern (and free) graphing software to see whether there are times for me and my family members to get together or avoid like the plague.
Will advise and, if successful, offer a freebie service for my forum friends. It’d while away a bit of time as a conversation piece, if nothing else. 