Hemophilia is a recessive X-linked condition and is inherited from parents. . The probability that Natalie and Daniel’s first child has hemophilia is 1/4, not 1/8. The statement is false.

<h3>What is an X-linked gene?</h3>

When talking about sex-linked genes, we refer to all those genes located in one of the sex-chromosomes and not in the somatic ones.

X-linked genes are the genes located specifically in the X sex chromosome.

Traits coded by these genes are inherited. This is, X-linked genes are transmitted from parents to children through generations.

According to this, X-linked genetic disorders will be inherited as well.

Men have a high probability of being affected since they only have one copy of the X chromosome.

In women, the effect of the mutation might be musk in heterozygous state if the mutation is recessive.

Hemophilia is a recessive X-linked disorder, which means it is coded by the recessive allele.

X+ ⇒ X chrosomosome with Dominant allele

X- ⇒ X chrosomosome with Recessive allele

Genotype Phenotype

X+X+ Healthy woman

X+X- Healthy carrier woman

X-X- Hemophilic woman

X+Y Healthy man

X-Y Hemophilic man

Let us make a pedigree of these families,

Natalie's family:

Mother healthy carrier X+X-

Father healthy X+Y

Brother hemophilic X-Y

Natalie Healthy X+X- or X+X+

Natalie has 1/2 chances of being carrier X+X- and 1/2 of being X+X+.

Daniel's family:

Mother healthy carrier X+X-

Father hemophilic X-Y

Sister hemophilic X-X-

Daniel Healthy X+Y

He has 1/2 chances of being healthy X+Y and 1/2 of being affected X-Y.

According to the product probability rule, if events A and B are independent from each other, the probability of occurrence of both events together is

P(A∩B) = P(A) x P(B)

In this case,