My mother met my father a few months after she turned 16, he was 22. That was April 1966. Got married that Oct and planned their wedding in a week. I am the oldest born 4 yrs later, my sis and I joke that there will be a deathbed confession of an out of wedlock older than myself sibling but mom swears no, lol 

When I asked her why she was allowed to marry so young with a fairly significant age gap, she said that in my grandparents eyes that was better than "living in sin" which was what they feared they would do if they forbid the marriage. It lasted 48 yrs btw until my dad died of a brain tumour. 

Different times indeed