SR Gene Region
The sex-determining region (SR) of the Y chromosome contains the SRY gene. The analogous sex-determining region (SR) of the X chromosome lacks the SRY gene. An individual without any SRY gene will develop into a female. Having an SRY gene will trigger male development.
Alleles
People normally have two alleles per gene, one inherited from their mother and one inherited from their father.
X (Global)
This allele has been widespread globally for tens of thousands of years.
Y (Global)
This allele has been widespread globally for tens of thousands of years.
Allele Pairs
It is the combination of a person's pair of gene alleles that influences traits.