Why are you a picky eater? Some of the reasons may include conditioning but there is a genetic portion as well. There's a gene that regulates how bitter certain foods taste and this is often the cue by which picky eaters shun a food. That gene, amongst other factors, is TAS2R38 and it triggers from glucosinolates in plants. Some theorize it existed to keep humans from killing themselves eating poisonous things in our more primitive days.