Why do these kittens look nothing like their mother?

This is a photograph from the Reddit.com website and the person who posted it asked: “Why do these babies look nothing like their mother?”

Superfecundation in action probably
Superfecundation in action probably. Photo: Reddit.com
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There are two reasons. The first is superfecundation which means that when you see a litter of kittens as you do in the photograph, they might have more than one father. In fact, they could be as many fathers as there are kittens. That means the genes carried by the father which dictates the father’s coat type and colour is multiplied several times which creates a very complex inheritance for the newborn kittens. The second reason is that some genes which dictate the coat colour and type are dominant to others. For instance, the white gene is dominant and masks all other colours completely. The tabby gene (agouti gene) is dominant over the non-agouti gene which is the gene for solid colour.

In the photograph there appears to be two white cats with faint tabby M markings on their forehead. There are two cats with more pronounced tabby markings and a solid light fawn-coloured coat. And a fifth kitten with a tabby coat and a more pronounced M marking on their forehead. There may have been three fathers.

The key factor as to why it appears that the mother cat could not produce the kittens is because she has possibly mated with several different fathers. Male cats squabble over a female in heat. The female is promiscuous enough to allow each to mate with her.

Her reproductive tract will, therefore contain the sperm of several males. This results in a litter of newborn kittens with a variety of coat colours and patterns that might not match their mother’s coat.

They say that this orgy of sex by different males with one female is a domestic or stray cat pattern of behaviour because wild cats live in much lower densities and therefore a single male will mate with a single female in heat. Strays can live in colonies.

In about 10% of female cats coming into heat superfetation occurs. This is when a second set of eggs is fertilised before the first litter is born. An additional period of oestrus occurs around three or six weeks into pregnancy which lasts nine weeks. If the female mates again and her eggs are fertilised, she’ll carry two litters at different stages of development. She’ll possibly give birth to kittens with different ages.

Here’s two definitions:

Superfecundation: the fertilisation of two or more eggs from the same estrus cycle by sperm from separate acts of sexual intercourse.

Superfetation: the occurrence of a second conception during pregnancy giving rise to embryos at different ages in the uterus.


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