Respuesta :
if blonde is 'b' and brown is 'B', the parents could have both been Bb; therefore resulting in a 1/4 chance of John being blonde
B b
B BB Bb
b Bb bb
The only way for John to have blonde hair is for both his parents to have one recessive gene.
B BB Bb
b Bb bb
The only way for John to have blonde hair is for both his parents to have one recessive gene.