Selectric
Tier-1 Mod
All of the ideas thus far pretty much covered most if not all the bases. The only factor that i did not see is you and your family. If you've experienced things throughout life, your energy could also contribute towards this. It could be a reach, but it's all theory until a definitive answer is stamped into stone. After the playback happened perhaps around that time just thinking about it could 'squeeze the initial trigger'. We all exude energy outward in some way. I doubt it's the catalyst but i'm sure somehow our energy effects unseen forces.