Difference Between Half Brother and Step Brother

Main Difference – Half Brother vs. Step Brother

Brothers are male siblings that share one or both parents in common. If we analyze this relationship in depth, we can see that there are different definitions and variations to the term brother. Brothers can be full brothers, half brothers, or step brothers. Many people do not fully understand the difference between these words and often assume that all these words mean the same. But this is not so; full brothers are the siblings that share the same parents, half brothers share one parent in common while step brothers are not biologically related. In this article, we are going to focus on half brothers, step brothers. The main difference between half brother and step brother is that half brothers are related by blood and share 25%  of genes whereas step brothers are unrelated by blood.

Who are Half Brothers

Half brothers share only one parent instead of two parents, unlike full brothers. Half brothers can be the male children that your father has with someone other than your mother or the children your mother has with someone other than your father. In short, half-brothers are the children born to your parent and stepparent.

When talking about the genetic relationship between half brothers, they share 25% of DNA. Half brothers can have different types of interpersonal relationships; some half brothers can share a very close bond while some half-brothers can be distant as strangers.

Half brothers who share the same mother are known as maternal half brothers while half-brothers who share the same father are known as paternal half brothers. In addition, some people consider that their paternal siblings as half-siblings and maternal siblings as their full siblings. This is because maternal siblings share a womb and children are usually raised by the mother.

You can understand the term half brother better by looking at the family tree below.Difference Between Half Brother and Step Brother

Who are Step Brothers

Step brothers are siblings through marriage and are unrelated by blood. They are the children of a step parent.  In short, step brother is the son of your step mother or step father. So the relationship between step brothers is not one caused by blood, but by law. But this does not mean that step brothers do not share a close bond. If they grow up together in the same family environment like full brothers, they’ll share a close bond.  In fact, some siblings share a closer bond than full siblings, irrespective of their blood relation. You can understand the relationship between step brothers by looking at the chart below.Main Difference - Half Brother vs Step Brother

Difference Between Half Brother and Step Brother


Half brother is a brother with the same mother but a different father or with the same father but a different mother.

Step brother is a son of one’s step-parent by a marriage other than that with one’s own mother or parent.


Half Brother is related by blood.

Step Brother is related through marriage.


Half Brothers share 25% of their DNA.

Step Brothers are not related by blood.Difference Between Half Brother and Step Brother - infographic

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