I understand Ashkanazim not eating the things prohibited in Europe and Asia at the time of the kitynot ban. Why did we add to the ban many inexpensive New World(from the Americas) things like corn or peanuts yet now allow quinoa. I am from a Yekka(German Jewish) family background but I and my sons have cilliacs.
Shalom, Thank you for your question. Much has been written about the custom of kitniyot, and the question you raise is a point of major debate amongst the Rabbis. There are those who understand the custom not to eat certain types of food, as coming to define characteristics that determine what kitniyot is and what it is not. Based on this understanding it would not matter if the food was know at the time of the prohibition or not – if the new food fits the criterion defined by the original foods, it will be kitniyot. Based on this quinoa will be a forbidden kitniyot – and there are rabbis who do ban it for this reason. However, if we follow this logic, it would seem that potatoes should be deemed kitniyot, (also a new world food), as we make potato flour out of them. And though there is such an opinion, the accepted practice is to allow potatoes (Baruch Hashem!). Other rabbis take a different view, and define kitnoyot based on custom. Those foods that we have a custom to consider kitniyot are forbidden, and those which are not are allowed. Based on this quinoa (and peanuts in many communities) which were never considered as kitniyot will be allowed. The problem with this opinion is the question of why did some foods from the new world become forbidden (such as corn) and others not (the potato)? However, this opinion doesn’t worry too much as to the historical process, but just accepts the facts as we see them today – that which we are accustomed not to eat is considered kitniyot. There are other opinions, but all of them have difficultly adequately determining and defining exactly what is and isn’t kitniyot. Therefore there are many varied rulings on this matter, with even some Sephardic communities refraining only from rice, others allowing only fresh green kiniyot, but not other types; some Ashkanazim allowing peanuts, and others not etc. The general ruling for questions like these is to follow one's family customs. If your medical condition makes that difficult for you, you should personally speak to a rabbi to see if your case warrants being lenient. May you be blessed with a great Pesach!