The sign of early baldness is dominant in men and recessive in women, while not sex-linked.

The sign of early baldness is dominant in men and recessive in women, while not sex-linked. Katerina, a woman with early baldness, married Peter, who had normal “hairiness,” and they had a daughter, Elena. Elena married Vladimir, who began to go bald early, and they had a daughter, Anna, who went bald early. With what probability (counting from the total number of offspring of both sexes) their next child will be female with normal hair growth.

Dominant trait – a trait that prevails over others, i.e. is stronger, indicated by capital letters (e.g. A, B, C).

A recessive trait is a trait that is suppressed by the action of another, i.e. is weaker, indicated by small letters (for example, a, b, c).

Homozygote – an organism or cell that contains the same gametes of the same gene, indicated by the same capital letters (for example, AA, BB, CC).

Heterozygote – an organism or cell that contains different gametes of the same gene, indicated by one uppercase and one lowercase letter (for example, Aa, Bb, Cc).

XX – female organism;

XY is a male organism.

By condition:

The sign of early baldness is dominant in men, which means that its genotype will look like AA or Aa (AA, Aa – baldness; aa – normal growth).

and is recessive in women, which means her genotype is aa for this trait (AA, Aa – normal growth; aa – baldness).

A woman with early baldness aaXX, married a man with normal “hairiness” aaXY and they had a daughter with the aaXX genotype, their daughter married a man who began to go bald early AaXY, we will make a Pennett lattice to find out how likely they will have a daughter with normal hair growth.

It can be seen from the grid that the girl with normal hair has the AaXX genotype and makes up 52% ​​or 1/4 of all possible children.

Answer: 1/4