A hemophilic man, right-handed (his mother was left-handed) married a left-handed woman with normal blood (her father and mother were healthy). What kind of children can be born from this marriage?
As you know, in humans, the ability to better control the right hand dominates over left-handedness. Let’s designate the gene that determines this ability as K, then the left-handedness gene will be k.
As you know, the gene that causes the development of hemophilia is inherited in the X – chromosome. Let’s designate the chromosome with the gene causing the blood coagulation pathology as X g. The chromosome with the normal folding gene is designated as X G.
Since the man’s mother was left-handed and had a homozygous kk genotype, she could only pass on the recessive k gene to her son. Therefore, this man is heterozygous for this trait.
The man has the genotype X g YKk, he produces four types of spermatozoa – XgK, Yk, X g k, YK.
A woman with better control of the left hand and free from hemophilia has the genotype X G X G kk and produces the same type of eggs X G k.
The offspring of this married couple will be represented by the following options:
right-handed girls who are free from hemophilia (X G XgKk) – 25%;
left-handed boys, free from hemophilia (X G Ykk) – 25%;
left-handed girls who are happy with hemophilia (X G X g kk) – 25%;
right-handed boys without hemophilia (X G YKk) – 25%.