Nobody really knows for sure. Some claim she was around 14-16, others say 12-14.
In my opinion I'd say around 16+, why because? I don't believe my God would make a virgin woman conceive if she is only 12 years old, her body would not be fully developed or ready. Then again I'm not God so I do not know.
you will all burn in hell for this!!!!
Then he called all the young men of the family of David, and promised Mary in marriage to him whose rod should sprout and become the resting place of the Holy Ghost in form of a dove. It was Joseph who was privileged in this extraordinary way.
Modern Christians would say "Well, customs were different in those times- people died a lot younger and had to start earlier."
Poor bugger, if it's not bad enough having to look after someone else's kid he's got a sprouty rod thrown in for good measure.