Thanks a lot Kora , I totally understand that these are general possibilities but I was trying to analyze these possibilities with you, discussing more details  about their case compared to the possibilities :) 

I really appreciate your help as I need to dig more , 
1. How can we dig about their ancestors especially that they passed away , and the ones living has no issues at all with fruits or veggies , in this case we exclude this or there’s a way to reach that information ? 
2. Regarding this point no stories as far as i remember were told but Watching on tv may be  but I can’t even confirm this with them as they don’t remember anything but do how did we relate this to New brain ? Is it a devaluation or self worth issue or something related to communicating with others ? 
3. He loses his voice when I force him to eat it by telling him if you eat it I will give you something you like this way he’ll eat it but it’ll not be his choice to eat I think it’s like an invasion of his territory .