What DNA Do Family Members Share?

Males with a common father

Sib males should share common Y chromosome alleles if they have the same father. However, they will also share these with any male relative in the paternal line, eg uncle and paternal male cousins.

Females with a common father

Sisters will share all paternal X chromosome alleles. A suitable number of X chromosome loci must be used to reduce random matches.

Sibs with a common mother

Mitochondrial DNA (mtDNA) is inherited through the maternal line. Again, it must be remembered that all individuals related through the maternal lineage will share mtDNA alleles (eg maternal aunts and cousins).