There was something about the Rothschilds family photo that bothered me.
Look at how old most of them are. There are few who are breeding age. For a family that size there should be many more breeders and an asspile of small children. But there is nether. Look.
In other words, they have inter-breed themselves nearly out of existence. Let that sink in for a bit.
So the obsession with blood – they are spending all their riches searching/ hoping to find lost family so they don't get lost to history.
They don't want their lineage to disappear as all the ancient lineages before them.