The gene (cv) is recessive and is known to be 13.7 Map units from the beginning of the chromosome. The recessive gene (f) is 51.7 map units from the beginning of the chromosome. After doing all of the calculations i found my gene order to be we-cv-f. Gene (we) is the unknown gene which i mapped to be 17.2 map units from gene(cv). This puts the unknown gene off of the chromosome by 3.5 map units.

Why is this? What are some possible genetic explanations for this?

Please assume all calculations are correct and when this experiment was performed around 400 fly's phenotypes were scored.