Is It okay for my girlfriend to bathe with her cousin (Female)?

So my girlfriend told me that she bathes with her cousin. And they have done it a lot. And hearing that from my girlfriend made me uncomfy. I dont know If Im wrong or right. Can anyone share their opinions?

And Ages are my girlfriend:- 14 and her cousin:- 12

Apart from the ages.

Is It okay for my girlfriend to bathe with her cousin (Female)?
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