Is Sweden Progressive or Not?

I thought Sweden was more advanced than this, seeing as how they will allow half-siblings to marry, though only with government approval. But here I found this article from back in March, where consenting adults were being prosecuted for having sex just because they’re siblings.

A pair of siblings in Kalmar in south east Sweden have been charged with incest and risk facing up to a year each in prison if found guilty.

A year in prison? And who was the victim of this “crime?”

The pair, both in their twenties, live very close to each other but in separate apartments, according to local newspaper Östra Småland.

They’re consenting adults.

Neither party is believed to have been subjected to coercion or violence, but as sex between siblings is illegal both could face time in jail.

It was consensual. Why prosecute? Why is there a law against this?

I was unable to find an update, so I don’t know what has happened since that article was published. If you have an update, please let me know.