Stranglíffræðilega skilgreiningin byggist einmitt á Y litningnum. Af wikipedia: Most women have the karyotype 46,XX, but around one in a thousand will be 47,XXX, and one in 2500 will be 45,X. This contrasts with the typical male karotype of 46,XY; thus, the X and Y chromosomes are known as female and male, respectively. Og eins og ég segi líka þá er stranglíffræðilega skilgreiningin ekki endilega mikilvæg í almennu tali.