How many of the choices you made in high school actually affect your adult life today?

Was talking about home economics as a school subject in another thread and i realised that for me personally, taking "Food Tech" (cookery gcse) would have impacted me pretty negatively, even though generally speaking GCSEs don't have much of an effect on the rest of your life or education.

So i wonder if anyone else has similar revelations? My post title is also phrased more openly than that, so it doesn't have to be school specific, but i am mainly interested in things from the teenage time period.