<P> Half - siblings are people who share one parent but not both . They may share the same mother but different fathers ( in which case they are known as uterine siblings or maternal half - brothers / half - sisters ) , or they may have the same father but different mothers ( in which case , they are known as agnate siblings or paternal half - brothers / half - sisters . In law , the term consanguine is used in place of agnate ) . They share only one parent instead of two as full siblings do and are on average 25 % related . </P>
<P> Half - siblings are people who share one parent but not both . They may share the same mother but different fathers ( in which case they are known as uterine siblings or maternal half - brothers / half - sisters ) , or they may have the same father but different mothers ( in which case , they are known as agnate siblings or paternal half - brothers / half - sisters . In law , the term consanguine is used in place of agnate ) . They share only one parent instead of two as full siblings do and are on average 25 % related . </P>
if you have the same mom but different dad
if you have the same mom but different dad
uterine siblings or maternal half - brothers / half - sisters
uterine siblings or maternal half - brothers / half - sisters