Why does cauliflower is high in purines while broccoli is not? thank you :)

Found in all living: organisms, purines are necessary to build genetic material/DNA. Protein foods are the richest sources of purine, but some fruits/vegetables have higher amounts as well. I think that's all we can say: WHY there are higher amounts of purines in artichokes, bean sprouts, broccoli, pea pods, etc. is beyond our knowledge. BTW, cauliflower is moderate purine food, along with spinach, mushrooms, corn..