What Is a Person with the Same Father but A Different Mother Called?

Family trees can be hard to determine, and all the different terms used to describe members of the family are complex. One family position that’s hard to determine is when two people have the same father, but a different mother. What does this make them?

If two kids have the same father, but a different mother, this makes them paternal or agnate half-siblings. Kids who share a mom but not a dad are called maternal or uterine half-siblings. If two kids only have one parent in common (whether it be the mother or the father), then they should be referred to as half-siblings because they have one but not both parents in common.

The rest of this article will cover what a paternal half-sibling is, and what a maternal half-sibling is.

What A Paternal Half-Sibling Is

Paternal half-siblings, also called agnate siblings, are two or more children who have the same father, but not the same mother. Most commonly, you can just say “half-sibling” to describe someone with those traits, but paternal half-siblings is the specific term.

Half-siblings differ from full siblings because full siblings share the same parents, both mother and father. Meanwhile paternal siblings share only the same father. No matter if the kids share a mother or father, if they don’t share both parents, you can call them “half-siblings”.

One of the main differences between full and half-siblings is that full siblings share around fifty percent of their genes while half-siblings only share twenty-five. Some prefer to say they have a blended family rather than call themselves paternal half-siblings.

Paternal half-siblings only refers to half-siblings who share the same father, so do not call half-siblings who share the same mother paternal half-siblings. Instead, you would call them maternal half-siblings.

What A Maternal Half-Sibling Is

Maternal half-siblings, also called uterine siblings, are two children who have the same mother, but not the same father. Just like paternal siblings, you can just say “half-siblings” to describe them, but maternal siblings is the specific term to describe two kids who share a mother but not a father.

Along with that, you can’t call two siblings who share the same father but not the same mother maternal half-siblings. This is because the term maternal half-siblings is reserved for siblings who share the same mother, but not the same father.