A doctor has left TikTok users fascinated by revealing how a set of twins can have completely different fathers.

Newborn intensive care specialist Dr Michael Narvey, 49, from Winnipeg, Canada, explained two possible ways the rare phenomenon can occur.

Firstly, he shared that twins can be conceived with different dads if "a woman has sex with two different men prior to her ovulation and the sperm are present in the fallopian tubes when two eggs are released".

Secondly, twins can also be fathered by different dads if a woman sequentially has sex with two different men after ovulating and the sperm are then able to fertilise two eggs.

Dr Michael finished the video by reassuring watchers that this is an "exceedingly rare event" and that they shouldn't worry too much about it ever happening to them.

The video has been viewed over 15,000 times and although many people were amazed by the idea, others were distracted by the bizarre scientific term - superfecundation.

One person commented: "Excuse me doc...What did you just say to me?"

"I thought you were saying a bad word," another user said.

Another person commented: "I think the name sums it all up!"

"I thought the name was a joke it's not," said another.

One confused commenter asked: "Why do they have to name it that?"