Background and Context: While biology has strong female representation, computer science is the least gender equitable of the STEM fields. A better understanding of the barriers that keep women out of computational fields will help overcome those barriers to create a more diverse workforce. Objective: We investigated the complexities that influence students' major choice and their sense of belonging. We were particularly interested in students adjacent to computer science and differences by gender. Method: We conducted semi-structured interviews of nineteen students from computer science or bioinformatics courses. We used inductive thematic analysis that included iterative readings of interview transcripts, line-by-line coding, and final theme selection. Findings: Most students described pressures stemming from traditional gender roles as they chose their major, but specific pressures differed by gender. Men were more likely to report early exposure to their major field, and women noted feeling behind without those early experiences. This hurt the women's sense of belonging, as did having few female peers. Implications: Increasing early exposure to coding may increase women's representation and sense of belonging in computational fields. Women from contexts with emphasis on traditional gender roles may be drawn to computational fields if they see opportunities for flexible positions.