It makes sense that if it was reported (it is in some places..possibly reported.. such as the Essenes... Their was one sect of the Essenes that marriage is ok...there were more than one sect as far as what I've read.)
But considering the "danger" these children would be in ... that in itself gives way to understanding why there was a need to hide the blood line. Do we know of many children of Kings that were tossed off their throne? How about the line of the Cleopatras...? Much reason to deny the liniage... you'd be saught out and killed.
There is much reason to hide the liniage.