The yellow body gene (y) and bobbed hair (B) gene are present 66 map unit apart which means that there is <50% chances of recombination between them (recombination frequency). Related Theory One map unit is equal to 1% recombination frequency. This linear relationship holds true for lower values only; as the recombination frequency increases beyond 50%, the linear relationship does not hold true owing to double and multiple cross overs and recombination frequency is always less than map distance and never exceeds than 50%.