Male-pattern baldness is a X-linked recessive trait, labelled X^{\text{b}}

b

start superscript, start text, b, end text, end superscript, with the dominant normal hair gene being X^{\text{B}}

B

start superscript, start text, B, end text, end superscript.

A father with the genotype X^{\text{B}}

B

start superscript, start text, B, end text, end superscriptY and a mother with the genotype X^{\text{b}}

b

start superscript, start text, b, end text, end superscriptX^{\text{b}}

b

start superscript, start text, b, end text, end superscript have a son.

What is the percent chance that the son will inherit male-pattern baldness?