Nowadays, I categorize people who ask me into several groupings:
Strangers - response is "I dont drink". 99% of the time the query stops there. No need to further explain and they are not interested. If it does, then I simply shrug and say 'I dont like it'. End of query.
Acquaintances/Friends of friends/Fair weather friends: I usually say that I dont drink for reasons of faith. This is true as I practice Buddhism. But usually by mentioning the word 'faith', folks simply nod and dont pursue questioning. As well, 'faith' can have many interpretations (eg, faith in a higher power). Folks within this group only pursue further querying as they want gossip. I brush them away.
Closer friends: I tell them the truth in that I drank too much in the past and it was ruinous for my health. As well, it was impacting family life. I decided to stop drinking for everyone's sake. These folks will immediately offer support which is greatly appreciated though not necessary anymore.
Close friends/immediate family: they know the truth and supported me through the toughest times.
The only category not mentioned is distant families as I rarely, if ever, meet them.
In the past 6+ years, I've only had one friend who hounded me on why I did not drink. He kept trying during the entire dinner to get me to drink even to the point where his partner asked him to stop as he was embarrassing everyone. It was a reflection on him and not me.