I think the question is trivial in the case of biological life. In the case of artificial life it becomes more interesting and Data is a self-aware being without emotions.
The difference between us is that you search for some causality whereas I locate consciousness in the above mentioned gap between the whole and the sum of its parts. Back to Data, think about why this unemotional machine often appears to be more human than us. There is nothing in his programming that explains it so you have to locate his "already more human than he thinks he is" trait in the gap. It is like the mysterious X that makes music out of single notes, a unique relationship out of two people and society out of single individuals.