My mother had a very logical, mathematical mind. That meant that she liked to have things even. My father, on the other hand, had a very artistic mind. He preferred things to be odd in number. The two of them had a constant battle over the symmetry of plants and decorations on the shelves and tables in the house.
Mom would always put out two or four of something. Dad would take one away to make three. The two of them would go back and forth with it, making each other crazy. At the same time, they were just trying to fulfill their own needs. My poor mother was finally outnumbered when my sister took after my father.
I am like my mother and tend to prefer even numbers. I have to take an even number of M&Ms in my hand at one time. I can't handle eating an odd number of things, unless I close my eyes and don't pay attention. The difference between my mother and I is that I can see how odd numbers can be made symmetrical and am okay with that.
To honor my mother's symmetrical mind, my father did give in once when he created a special painting just for her. It is in various shades of blue, which is her favorite color. The patterns are even in number and in perfect symmetry. He once told me that it was very difficult for him to let go of his own patterns, but wanted to do this for her. It is currently hanging in her room at the nursing home. She doesn't remember from whom it came, but it makes her happy to have it there.