actual studies done on racial preferences across both sex's and across different racial groups

Oh, "actual studies", why didn't you say so?

So, where are these "actual studies"? Got some links? Or are you just repeating what you've been told, like a parrot, without ever reading the studies or even checking whether they exist? Let alone whether they are good credible studies?

it also wasn't even terribly common even back then.

A couple of examples that show that this was not rare even at the very top levels of American society:

• Thomas Jefferson (a white man) had six children with his slave, Sally Hemings, a black woman.
• The ninth vice-president of the United States, Richard Johnson, had the mixed-race dark-skinned slave Julia Chinn as his common-law wife, and had two children by her, acknowledging his paternity and insisting that they take his surname.

So called "mulattoes" from white slaver fathers and black slave mothers were not rare. By 1870, twelve percent of American blacks were legally considered as "mulettoes" or "half-castes". That is surely an underestimate, for reasons which I trust will be obvious:

• white slaver fathers in the 19th century would rarely acknowledge their paternity;
• people with black ancestry who could pass as white would have enormous social and economic incentive to claim to be pure white;
• half-caste slaves were popularly imagined to combine the worst traits of both blacks and whites and were worth less, giving slavers an economic incentive to pass of mulatto slaves as full-blooded black African.

One need only look at the skin colour of American blacks to realise that there is surely a lot of unacknowledged white blood in their ancestry.

So-called "mulattoes" were common enough that the southern states had laws about them, declaring that they were considered slaves. Starting from around 1831 or thereabouts, the southern states passed laws preventing the slave owner father from freeing his children from black slave mothers.

In any case, until the general relaxation of race relations in the 20th century, there were three major sources of mixed-race children in the USA:

1. During the 17th century, there were large numbers of unions between low-status indentured servants (usually Irish women) and black slaves. This was common enough that in the second half of the century, Maryland, Virginia and North Carolina prohibited such unions.
2. During the 18th century, it was common for wealthy white men to have concubines among their black slaves, or free black mistresses. This was considered socially acceptable and even unremarkable, and the men would often acknowledge paternity and free their children and the mother.
3. During the 19th century, white plantation owners (the men, never the women) would often have children by their female slaves, but would rarely acknowledge paternity and (after 1830) were legally prohibited from freeing their offspring.

In the first case, the Irish were not considered "white" despite their pale skin. (Usually paler than most so-called "white people", which just goes to show what a crock of shit skin-colour racial categories are.) It was only later in the century, as the Irish slowly and gradually started to be considered part of the "white race" that the legal prohibition against intermarriage started.

And of course the USA is not the only majority white slave-owning country! The French, British, Spanish and Portuguese all had black slaves, and they too had a very relaxed attitude to white men having black mistresses (whether a free woman or an enslaved concubine).

To give just one example out of many, the author of "The Three Musketeers", French writer Alexandre Dumas, was the son of a mixed race Creole, Thomas-Alexandre Dumas Davy de la Pailleterie, or just Thomas-Alexandre Dumas for brevity.

Thomas-Alexandre Dumas was the son of the white French nobleman the Marquis Alexandre Antoine Davy de la Pailleterie, and the black slave Marie-Cessette Dumas. His father the Marquis freed him and his mother, and took him to Paris where he was educated and joined the military, becoming one of revolutionary France's greatest generals. The Austrians called him the Schwarzer Teufel ("Black Devil") for his successes against them in the Second Italian Campaign. But I digress.

there are actual books written by, yes, actual jews, dating back to the early 1900s and upto the 60s, lots of lots of them

Only in the fevered imagination of jew-baiters.

Did you skip the math lesson where they taught basic addition, perhaps?

Is that the lesson where you learned that 1 + 1 = 88?