Flip the Sibling

These two, made from the same genetic soup in the same womb, try to fuse themselves together. Like attracts like. What is the origin of this struggle? A silly wrestle? A game of "flip the sibling"? A fight for the mother's love?

This reminds of my sister in childhood. My sister Cate, who at this time in her life was known as Casey, always wanted to be with my mother. We were five years apart, she and I and this was a gulf the size of a canyon. For the first six years of her life or so, we were arch enemies. She took over my mother's attention from me with her ardent presence. She would cling to my mother, hug her legs, demand her lap and took all that doting, doting I had never needed nor acknowledged, and bathed in it. As an adult, Cate describes her attachment to my mother by saying she was shocked by being outside the womb and spent the first years of her life trying to find a way back into the belly.

Are all clingy children looking for that return to their mother's womb? Are these two depicting a physical representation of this wish to return to their genesis? Do they try to best each other subconsciously knowing, "There's not enough room for the both of us in there"?