The influence of sex on cellular function and metabolism is often ill defined in many human and animal studies. The National Institute of Health (NIH) recognized this gap in scientific knowledge and mandated that sex be factored into the design and data analysis of all cell culture and animal studies. Therefore, it is critical to understand how to incorporate sex in pre-clinical and clinical research. Here, we discuss how the sexual identify of cells influences experimental responses in cell culture and we highlight the importance of the culture media and its constituents to the function of cells. We further discuss the importance of understanding the influence and interactions between sex hormones and sex chromosomes. A deeper understanding of how sex chromosomes and sex hormones function as variables in complex biological systems may lead to better, more personalized medical therapies.