Converting from 2 year capture to 4 years without a 100 year?

Any tips on how to capture a full year age when converting from two years to a four year digit? Without asking for manual input?

The problem I think lands specifically for a 100 year age.

E.g. if we captured DDMMYY: 04/08/18 this person could be 100 years old eg 04/08/2018 or 04/08/1918. Is there any logic we can implement to manipulate this without asking for any user input?