Yeah, siblings will mate with each other. You might have sexed them wrong, and they're actually the same gender as each other. ..And why would you still want them to mate if they're siblings..? You do know that can result in genetic anomalies and medical illnesses in the offspring, right? That isn't fair to the babies.

 

Don't breed them simple as that.

Why do you want to breed anyway? If you truly want to breed,I would not do it now,Instead I would do as much research as I possibly could and then some.Breeding takes more then throwing a male and female together.

Siblings WILL mate,but they shouldn't.Inbreeding can cause problems.I would seperate the male and female RIGHT NOW.If your female did get pregnant and have the babies,she can get pregnant again soon after giving birth and at about 5 weeks,the gerbils can breed and will breed with eachoher and the mother...this results in "too many" gerbils.

 

I agree with what the others have said.

Do you realise what could happen as a result of inbreeding? You could have pups that are missing limbs or even eyes! That isn't fair on the pups and it isn't fair on the mother.