Answer 1:
That's an interesting question. Human males
and females typically display equal amounts of
dominant and recessive traits. We get 2 copies
of each gene on each autosomal (non-sex
specific) chromosome: one set of copies from our
father and one from our mother.
A recessive gene causes a phenotype (an
expressed characteristic) when an individual is
homozygous for that gene (has 2 copies). A
dominant trait will be expressed with only one
copy of the gene (heterozygous). Therefore,
whether a person is recessive or dominant for a
given trait will depend on their parents'
genetic makeup. Traits can also be semi-dominant
(the genetics that determines our blood types
are an example of this).
There are certain traits and diseases that
are linked to genes that are on the X chromosome
only (females are XX, males XY). So if a male
gets one of these genes on his X chromosome
(from his mother), he will express the trait,
whether it is dominant or recessive (because he
has only 1 X chromosome). If a man has an X-
linked dominant trait, his daughters will
express that gene (they get his X chromosome; if
it is recessive, they will be a carrier of that
gene). In contrast, if a mother has an X-linked
dominant trait, her daughter's have a 50% chance
of receiving that trait.
I hope this answers your question!
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