There is a very specific, and rather amusing, reason some chinese avoid allium vegetables.
2600 years ago, in the time of the buddha, the buddha saw one unhappy monk sitting apart from his friends. He saw something was up, so he went to the monk and was like 'dude, why arent you sitting with your friends?' The monk said a lay person presented him with a whole bowl full of raw garlic and he took it... and ate the whole bowl, raw, and now his friends said he stinks and they wont sit with him today. The buddha sort of nodded and said 'if you like sitting with your friends then in the future dont eat whole bowls of raw garlic'.
The moral was very obvious in the sutta, if you want to get along with people some times you need to make trivial harmless compromises.
The chinese took the story wildly out of context, ignored 80% of it, and just say "buddha says dont eat garlic"
The chinese really like allium vegetables, really.
A wonderful example of why, if your going to follow a religion, you should actually learn
what the religion really says!
Nearly all cultures use alliums in some way, even northern european cultures that say they hate garlic rub salad bowls with it so the salad smells garlicy.