Lavender Color Question

Is it normal for a lavender corn snake to have a yellow color near the head and neck region? I know my snow has the yellow color but I was just wondering about the color being present on lavender corns. A long time ago I was told the yellow color develops due to a diet of mice and rats in captivity but I'm not sure if that's true or not.

None of my adult lavenders have any yellow on them. Anery and sometimes charcoal can have yellow. Especially anery, the yellow comes in as they age, and I've never heard of it having anything to do with diet.