Since food intolerance runs in families, I would expect identical twins to be affected by the same food chemicals, so when this mother wrote about the reaction of a twin to the bread preservative, I asked whether the other twin was affected. You can see her answer below. This is an excellent illustration of how parents are more likely to identify behavioural reactions to food chemicals and to miss other types of reactions. Yet usually if one member of the family is affected, others will be affected in different ways.

I am the mother of identical twin girls aged three and a half. I have discovered that one of my twin girls reacts violently to the preservative 282 in bread and since my girls were 18mths old have been purchasing bread through Baker Delight with great success. Recently for the first time in two years she was eating preservative bread on holiday and went off her head.  Screaming, tantrums, the whole nine yards so to speak … later … When you asked does my other girl react differently, I really had to sit down and think about this one. Yes I suppose she does. It seems to me that her ability to hold her bladder disappears while being affected by 282, that is, she says she needs to go pee, then her pants are wet. Off 282 for a few weeks, mentions she needs to pee in the middle of grocery shopping, I have time to quickly finish off shop then get trolley through the checkout and then get to toilet. A big difference. At home now she will need to go, but can keep playing for about 2 – 5 minutes whereas if she is eating 282 and needs to pee, she will pee on floor on the way to bathroom. – by email.