One really must be very careful how one goes about this business of anything being in the blood.
On the vain glorious assumption that one can trace one's ancestry back a few hundred years or so, certainly far further back than the first colonisers of the Hottentot lands; any familial characteristics which might have flowed from the first generation to the last, might reasonably be said to be in the blood.
Anything much less than this is simply pure nepotism.
Toodle Pip.