Grandpa’s old gin, no alcohol flavor.

I have no idea on the year, this belonged to my grandpa who passed a few years back. My wife just had our beautiful daughter, I thought I’d open this to celebrate. Took the plastic seal off (yellowed) poured a sipping glass, and it tastes like weak tea or dirty water with no alcohol. I’ve never had gin before though… Is this what gin is like? (Unlikely) Could this have had a leak and the alcohol evaporated? Maybe my grandpa put tea in to mess with whoever got it? Kinda bummed it doesn’t seem alcoholic, but c’est la vie.