A social media user presents four pictures of four different kittens. They were found with a stripey mum. The person asks whether all of the kittens could be hers. The photographs are below courtesy: u/s-dai.
The answer is yes because kittens in the same letter can have different fathers. The process is called superfecundation.
We don’t have a photograph of the stripey mum but she must be a mackerel tabby.
Looking at the kittens, one well-informed social media user decided that the two fathers for this litter would have been (1) a grey tabby and (2) an orange or ginger tabby.
They say that orange plus black or brown normally results in tortoiseshell cats. If the white spotting gene is present, they will be tortoiseshell-and-white cats. These are called calico cats in America.
The question is whether superfecundation can affect humans. It can. But very rarely. One study estimated that it might occur 0.25% of the time in twin births in the US. This is one in 400. That’s a guess because people don’t request DNA testing when they are suspicious.
It happens, as you can imagine when two different men in a short period of time have intercourse with an ovulating woman. She is impregnated by both men separately.
Apparently, there was a story from Cape Town which reported on triplets having different dads. A Cape Town woman give birth to triplets fathered by two different men. It led to a legal battle between a cabdriver who challenged the paternity of the children. She sued him for maintenance.
Another question is whether superfecundation occurs among the wild cat population. It doesn’t because the density of the distribution of mainly solitary wild cat species is such that only one male impregnates one female.
Superfecundation appears to be a domestic cat condition because of the density of the population of domestic cats in multi-cat homes in which the cats are not sterilised.
It occurs among feral and stray cats as well. There are feral cat colonies formed around a source of food. This would be an ideal condition for superfecundation.
A similar but different condition is called superfetation. This occurs when a second new pregnancy happens during an initial pregnancy. Another egg is fertilised and implanted in the womb after the first one. So, this is sequential rather than fertilisation happening at the same time in superfecundation.
Superfetation apparently has not been definitively demonstrated to occur in domestic cats despite case reports according to a study dated 2006. I think that is out of date. I did an article about superfetation some time ago which you can read by clicking on this link.