On my husband's side of the family there does seem to be a gene for exceptional memory. Some of the people have it, some don't and it is crystal clear who has it and who doesn't. My husband has it, my oldest daughter has it, my other daughter does not. Ask my husband any birthday or anniversary date on either side of our very large and extended family - no problem. Ask him to put together a piece of IKEA furniture and we are in trouble.