Is It Legal To Have Sex With Your First Cousin?

Is It Legal To Have Sex With Your First Cousin?
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Now that Game of Thrones is back, we’re getting exposed to a whole new season where certain characters enjoy keeping it in the family. Incest may be low-key tolerated in Westeros, but what about here in Australia? Is the whole notion of “kissing cousins” (and a whole lot more), illegal?

There isn’t any law that specifically mentions sex with first cousins in Australia, but there is one in regards to marriage. This is what section 23B of the Marriage Act 1961 has to say about it:

Marriages of parties within a prohibited relationship are marriages: (a) between a person and an ancestor or descendant of the person; or (b) between a brother and a sister (whether of the whole blood or the half-blood).

In other words, you can’t marry a direct ancestor or descendant or a sibling. But there is nothing there about preventing marriage between cousins.

And because marriage implies consummation, and there is no other law that prohibits this, what we can conclude is that sex between cousins is also completely fine here in Australia.

It’s worth noting that this law also doesn’t prevent sexual relationships or marriage between aunts, uncles, nieces or nephews.

So regardless of how anyone might feel about it, you’re legally in the clear when it comes to getting down with your cousin, so long as the parties involved are of legal age and have consented to the relationship.

Did you just catch yourself wondering if something was legal or not? Let us know and we may be able to answer it in our next Is It Legal? feature.


  • I am pretty sure there are laws against sex in a lineal descents, siblings and step children. So it’s just precluded acts and it doesn’t include siblings.

  • Well, my Uncle did marry my Step-Sister (his Nice and her Uncle) So I assume those close relationships are Ok. They did have a number of children but I don’t know whether to refer to them as Nices and Nephews or Cousins?

    • If the Uncle is a biological relation (i.e. brother of a parent), they would be your cousins, if he is an uncle by marriage (i.e. used to be married to a biological aunt), then you would call them your nieces and nephews.

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