Where do cooties come from?

In reference to this classic:

For over half a century I have not found a definitive answer to this question, “Do you get cooties from girls, or do you get cooties from boys?”

So far, informal polling shows a 50-50 split on the answer. Usually the girls insist you get cooties from boys, while the boys insist girls are the source. Now my knowledge of microbiology is limited, but this does not sound like the typical pattern of pathogens. One sex must be the source of these undesirable parasites. Does anyone know of definitive research in this area?

Girls are the source of Cooties.

There are two kinds. The one that you can see and the one you cannot. The name comes from the ones you can see. The term was originally the German ‘Kopflause’ (head louse/lice) and then English kids in the WW2 tried to talk about it, and why they were not allowed to touch other children, and pronounced it cooties. All know that girls back then had long hair and boys had short military style hair. Hence, the girls were more prone to have cooties and was the wisest to avoid more strictly.

I am from Sweden, here we just call what you call cooties in America and Great Britain for “tjejbaciller”. ~Girly germs. It is important not to touch girls since they then can infect you with girlishness making you giggle and wear pink and so on.

Tadaaaaa!

References:
Well, no, but true science never does. Check it out yourself.
Girls are icky.

Kopflaus is not the usually given source of cootie, and it seems a most unikely connection. It’s nothing but a literal equivalent of English “head louse”, and has no phonetic similarity to cootie beyond starting with /k/. Furthermore, laus is pronounced like louse, and many 20th-century speakers of English were familiar with the German kopf for head, if only because of the familiar comic use of dummkopf.

Cootie is generally believed to derive from Malay kutu, “flea” or “louse”.

So, still girls then?