Cultural indicators

Joining a new company means being alert to (and maybe embracing) any cultural conventions that are specific to that organisation. Over many year I have worked in companies where no-one has commented on the fact that I reply to emails without including the original (the one I am replying to) in my message. In my new company I've been asked by several people why my emails do not contain the message I am replying to. Today (four months in) I have bowed to convention (or pressure) and will start to include the original in my reply. My preference is not to do this as I like a clean page but maybe in order to fit in and get on I need to over-ride this particular preference of mine.