Dear intern,
I was a senior engineer with seven years experience. All the data in our production database was dropped. I quickly looked at the git history and found some check ins from the new guy that seemed to be a deleted where clause. Exasperated I pinged on hipchat: "HOW COULD YOU DO THIS". Then when doing `git log -S where` I saw to my horror it was MY code that first introduced it. He had just merged my branch into his.
EVERYONE MAKES MISTAKES.