When recruiting for the UAS, we had to ask the 'Big 3', which included asking whether the candidate had ever been involved with drugs. Any hint of a 'yes' meant GET OUT! I hope that is still the case?
When I joined in 1975, one of those questions was: " are you a homosexual?". At the time, gay people were banned from the military and women who got pregnant had their careers stripped from them.
In WWI soldiers suffering from post-traumatic stress disorder were shot for cowardice.
In the Roman Army, the penalty for retreating was to have every tenth squaddie beaten to death by his mates, using only their bare fists.
Times change mate...thankfully.