How do Labs get their coat color?
Short answer
Two main loci control classic Lab colors: B, which sets black versus chocolate, and E, which decides whether dark pigment reaches the coat. Chocolate Labs are bb and not ee. Yellow Labs are ee. The dilute D locus can further lighten coats.
Read the full guide: How Chocolate Lab Color Is Inherited →
Go deeper
Sources for this answer are cited in the full guide.